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term anatomy stems from the Greek word, ‘anatemnein’ which means to dissect, to cut apart. The important anatomist Hyrtl spoke consistently also of the art of dissection. The original meaning is true even today; although the term has gained a wider meaning. Modern anatomy is not limited to mere description but emphasizes the interrelations between form and function as well as the application of anatomical knowledge in the clinic. Then as today the student gains most of his knowledge by dissection of the animal body in the laboratory, where he lays bare the ‘naked truth’ (Nudas veritas). This practice also serves to obtain a necessary fingerdexterity, which in later professional life, in the first place in surgery, is of immeasurable value. Beyond that there are hardly any limits to investigation by enthusiastic dissection. Even the very best anatomical collection of outstanding demonstrationdissections cannot replace practical work in the laboratory, but can however indeed make it easier and more efficient. The thorough study of anatomical preparations is indispensable like the industrious use of textbooks and atlases. All of these aids are more important today than ever since there is much less time available for practical work in the laboratory than formerly. Shortening the teaching time allotted to anatomy in favor of newer disciplines was unavoidable. Anatomical study is, unlike any other basic discipline, important in learning the language of medicine, the terminology. Many terms for diseases and methods of treatment have their origin in anatomical terms. Centurieslong research and description brought an unforeseen abundance of synonyms. The function of the international nomenclature commission has been to thin out the jungle of terms and to publish a recognized list of official terms with useful synonyms. In its entirety, anatomy is subdivided into macroscopic (gross) anatomy, microscopic anatomy and developmental anatomy. However, the areas of anatomy flow together without boundary, forming a unit, an understanding constantly and forcefully advocated by the important Berlin veterinary anatomist and, at an earlier time, the professorial chair of our department, Professor Preuss. The oldest and most encompassing area is macroscopic anatomy, often placed equal to the term anatomy. Where the accessories to observation in macroscopic anatomy, the bare eye and the dissection hand lens no longer reach, it passes over into the area of microscopic anatomy (histology and cytology), to which the microscope serves as accessory. The boundary between macroscopic and microscopic anatomy is also called mesoscopy, which is gaining more and more in significance. The latter area deals with the same material and pursues the same goals; it is only the technique that is different. The third area, embryology, is concerned with ontogenesis (development of the individual) before and after birth and, in addition to embryological methods, applies also macroscopic, microscopic and mesoscopic methods. Like the remaining disciplines, macroscopic anatomy can be presented from different points of view with emphasis on special areas of greater difficulty. In so doing, the basic facts remain of course unchanged. Systematic, descriptive anatomy describes the animal body with all its parts as systems of structure and organsystems, strictly divided from one another and therefore without attention to their natural interdependence. Expansive descriptions treat many particulars and allow sometimes the view to the important to be missed; nevertheless they are a necessary prerequisite to the remaining, subsequent kinds of observations to which the descriptive anatomy has led. Systematic anatomy can be subdivided further into general and special anatomy. General anatomy treats of facts that are generally valid for the entire system of structure or the organsystem. Special anatomy provides special data for these structure and organsystems that hold for individual structures, as for one bone. Comparative anatomy emphasizes anatomical correlations, similarities and variations between the individual animal species and human beings. Comparisons of anatomy between the individual species are very often informative and helpful for homology and determining the function of anatomical structure. Already Goethe utilized principles of comparative anatomy to good advantage with the discovery of the incisive bone of human beings. This bone occurs regularly in our domestic animals and only occasionally in human beings. With his study of the human skull he encountered a specimen with a developed incisive bone. It was by comparison with the animal skull that he was able to identify the bone and establish its homology. Topographical anatomy emphasizes the varying positionrelationship of anatomical structures and underlines the areas of application for clinical medicine. The relationship of anatomical structures is analyzed step by step and in doing so the whole structural plan of the body is regarded. Applied anatomy is directed clinically and emphasizes the relationship of anatomical structures from which treatments or diseases of animals can be determined or explained. In that way not only interdisciplinary cooperation and interest for the veterinary profession are promoted but also the learning of anatomy is made easier. The anatomy of the living dog is undoubtedly a significant part of the whole of anatomy. It presents the body in its natural condition. In that way a significant completion and an adjustment for unavoidable disadvantage becomes imperative in the remaining subjects of the whole of anatomy, which must tolerate postmortem changes such as variations in color, consistency and character as well as artificial changes resulting from fixation. Anatomy of the living dog cannot be given attention here for several reasons. It is adaped even less for rendering in a book, but can be offered to the students better and more successfully in an exercise under the instruction of a clinically experienced anatomist. Radiographic anatomy and sonography are directly connected to the clinic. In the teaching of anatomy, the first experiences are obtained in analysis of radiographs of the normal animal body. This experience will be utilized and considerably supplemented in the total associated area of study. Presentations of abnormal or even pathological changes should awaken the interest and accordingly add ‘spice’ to the teaching of anatomy. The atlas of anatomy presented here is adapted in special measure to significantly combine and coordinate the different methods of presenting anatomy and the manner of viewing it. The textual part can be presented in a very compressed form since the different anatomical circumstances can be ‘read off’ from time to time from the adjacent colorplate. Beyond that, a good topographical colorplate presents an ideal introduction for topographical dissection, which is then completed only by brief remarks. Also the requisites of comparative veterinary anatomy are taken into account in this atlas insofar as the simply structured (from many points of view) canine body is set out as the ‘cornerstone.’ Building upon this knowledge, the more complicated (from many points of view) anatomy of the remaining domestic animals can be comprehended from the aspect of comparative anatomy. Art and anatomy with their mutual interrelations are forcefully impressed on us with each visit to a museum. The artist is inspired by the corporeal beauty, and teachers and students of anatomy enjoy and profit from the talent and painstaking detail in the artistic presentation. Gifted with genius were realized the claims of Leonardo da Vinci, whose abundant anatomical drawings came about after basic studies of anatomy. Aristotle published among other things an anatomical description of senile sexual reversal in the bird as well of the horse hoof in regard to founder. What fascination of anatomy passes over to art, Rembrandt immortalized in his work ‘The anatomy lesson of Dr. Nicolaes Tulp.’ The greats of world history gifted with genius like Aristotle, Leonardo da Vinci and Goethe show proof of their enthusiasm for anatomy with anatomical illustrations, descriptions and research results. To Goethe’s credit was the promotion of educational art and the introduction of plastic wax models in Germany, to which he, himself, was inspired during his journey to Italy, especially in Florence. The good qualities of wax models, which is true to an equal measure for well done truetonature illustrations, Goethe expressed in his novel ‘Wilhelm Meisters Wanderjahre’ with the following excellent formulation: ‘If you concede that most physicians and surgeons retain in their minds only a general impression of the dissected human body and believe that to satisfy the purpose; so such models will certainly suffice, which refresh in his mind again little by little pictures that are fading and actively retain for him just the necessary.’ His investigative mind held Goethe...

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9 783899 9301 84

Wolfgang Fricke · Renate Richter

Anatomy of the Dog

with Aaron Horowitz and Rolf Berg

The present volume of Anatomy of the Dog is based on the 8th

edition of the highly successful German text-atlas of canine

anatomy.

– Fully illustrated with color line diagrams, including unique

three-dimensional cross-sectional anatomy, together with

radiographs and ultrasound scans

– Includes topographic and surface anatomy

– Tabular appendices of relational and functional anatomy

“A region with which I was very familiar from a surgical standpoint

thus became more comprehensible […] Showing the clinical

rele-vance of anatomy in such a way is a powerful tool for stimulating

students’ interest […] In addition to putting anatomical structures

into clinical perspective, the text provides a brief but effective

guide to dissection.”

The Veterinary Record

“The present book-atlas offers the students clear illustrative

mate-rial and at the same time an abbreviated textbook for anatomical

study and for clinical coordinated study of applied anatomy.

Therefore, it provides students with an excellent working

know-ledge and understanding of the anatomy of the dog Beyond this

the illustrated text will help in reviewing and in the preparation

for examinations For the practising veterinarians, the book-atlas

remains a current quick source of reference for anatomical

infor-mation on the dog at the preclinical, diagnostic, clinical and

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Anatomy of the Dog Fifth, revised Edition

Professor Klaus-Dieter Budras

Institute of Veterinary Anatomy

Free University of Berlin

Professor em Patrick H McCarthy

Dept of Veterinary Anatomy, University of Sydney

Professor Aaron Horowitz

Professor Rolf Berg

Dept of Structure and Function

School of Veterinary Medicine

Ross University, St Kitts, West Indies

Science Illustrator

Wolfgang Fricke

Renate Richter

Co worker

Dr Anita Wünsche and Dr Sven Reese

Contributions to Clinical and Functional Anatomy by

Dr Sven Reese, Dr Klaus Gerlach and Professor Klaus-Dieter Budras

Introduction to Radiographic Technique and Ultrasound Diagnosis

Professor Cordula Poulsen Nautrup

Introduction to Computed Tomography

Dr Claudia Nöller

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Co-workers on the Atlas of the Anatomy of the Dog

Fourth and Fifth Edition

Prof Dr Hermann Bragulla, School of Veterinary Medicine, Louisiana State University, Baton Rouge, USA

Dr Klaus Gerlach PhD, Tierärztliche Praxis, Berlin

TA Claudia Herrmann, Institut für Veterinär-Anatomie, Freie Universität Berlin

Dr Ruth Hirschberg, Institut für Veterinär-Anatomie, Freie Universität Berlin

Prof Dr Dr h.c Horst E König, Institut für Anatomie, Veterinärmedizinische Universität Wien

Prof Dr Dr h c Hans-Georg Liebich, Institut für Tieranatomie, Ludwig-Maximilians-Universität München

Dr Claudia Nöller, Institut für Veterinär-Anatomie, Freie Universität Berlin

Prof Cordula Poulsen Nautrup, Institut für Tieranatomie, Ludwig-Maximilians-Universität München

Dr Sven Reese PhD, Institut für Tieranatomie, Ludwig-Maximilians-Universität München

Dr Anita Wünsche, Institut für Veterinär-Anatomie, Freie Universität Berlin

Prof Dr Paul Simoens, Faculteit Diergeneskunde, Gent, Belgium

Editorial contribution:

Dr Silke Buda, Institut für Veterinär-Anatomie, Freie Universität Berlin

Index:

Thilo Voges, Institut für Veterinär-Anatomie, Freie Universität Berlin

An index of earlier co-workers and of the sources for illustrations, radiographs, and photographs can be

obtained from the previous edition

© 2007, Schlütersche Verlagsgesellschaft mbH & Co KG, Hans-Böckler-Allee 7, 30173 Hannover

Printed in Germany

ISBN 978-3-89993-018-4

A CIP catalogue record for this book is available from Deutsche Nationalbibliothek, Frankfurt — Germany

All rights reserved The contents of this book both photographic and textual, may not be reproduced in any form, by print, photoprint, phototransparency, microfilm, video, video disc, microfiche, or any other means, nor may it be included in any computer retrieval system, without written permission from the publisher

Any person who does any unauthorised act in relation to this publication may be liable to criminal prosecution and civil claims

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Table of Contents

References vi

Introduction to Anatomy 1

Topographical Anatomy: Chapter 1: Surface of the Body and Axial Skeleton 1 Division of the animal body 2

2 Skin (common integument) 4

3 Cutaneous glands, modifications of the skin, digital end-organs 6

4 Vertebral column and thorax 8

5 Articulations of the vertebral column and of the thorax; atlanto-occipital joint and atlanto-axial joints (A WÜNSCHE and K.-D BUDRAS) 10

Chapter 2: Neck and Chest Region (Cervical and Thoracic Region) 1 Cutaneous muscles and cutaneous nerves of the neck and thoracic wall 12

2 Dorsal extrinsic limb muscles 12

3 Ventral extrinsic limb muscles 14

4 Nerves, vessels, and visceral organs of the neck 14

Chapter 3: Thoracic Limb 1 The skeleton of the thoracic limb 16

2 Medial veins of the thoracic limb; medial shoulder and arm muscles and their nerve supply 18

3 Lateral veins of the thoracic limb; lateral shoulder and arm muscles and their nerve supply 20

4 Antebrachial (forearm) muscles and their nerve supply 22

5 Vessels and nerves of the thoracic limb 24

6 Synovial structures of the thoracic limb (A WÜNSCHE and K.-D BUDRAS) 26

Chapter 4: Thoracic and Abdominal Wall 1 Muscles of the vertebral column, nuchal ligament and lumbar cutaneous nerves 28

2 Respiratory muscles 30

3 Body wall, prepuce, and mammary glands (Mammae) 32

4 Abdominal muscles, rectus sheath, prepubic tendon 34

5 Inguinal region, inguinal space (inguinal canal), neuromuscular and vascular lacunae 36

Chapter 5: Thoracic Cavity 1 Lungs, tracheal bifurcation and bronchi 38

2 Blood vessels, nerves, and lymphatic system of the lungs; aortic arch; lymph nodes of the thoracic cavity, thymus 40

3 Thoracic cavity, pleura, and veins of the thoracic cavity 42

4 Heart, surface of the heart, heart wall and relationships in the interior of the heart 44

5 Heart, coronary vessels, heart valves, cardiac conduction system 46

6 Autonomic nervous system 48

Chapter 6: Abdominal Cavity 1 Topography of the abdominal organs and relationships of the peritoneum 50

2 Peritoneal cavity, lymph nodes of stomach and intestine, cisterna chyli and spleen 52

3 Stomach and small intestine, pancreas 54

4 Large intestine, blood vessels of stomach and intestine 56

5 Liver and gall bladder (H BRAGULLA and K.-D BUDRAS) 58

6 Autonomic nervous system, abdominal aorta, caudal vena cava, sublumbar muscles and the lumbar plexus 60

Chapter 7: Urinary and Genital Organs, Pelvis 1 Urinary organs 62

2 Urinary bladder and peritoneal relationships of the genital organs 64

3 Female genital organs 66

4 Male genital organs, lymphatic system of the lumbar and pelvic regions 68

5 Arteries, veins and nerves of the pelvic cavity, adrenal glands 70

6 Pelvic diaphragm, ischiorectal fossa; associated arteries, veins and nerves 72

7 Smooth muscle of the pelvic diaphragm and the bony pelvic girdle 74

Chapter 8: Pelvic Limb 1 The skeleton of the pelvic limb 76

2 Muscles of the hip joint and their nerve supply 78

3 The medial saphenous vein, obturator nerve, femoral nerve, medial thigh muscles, femoral space (femoral canal) 80

4 The lateral saphenous vein, common peroneal nerve and tibial nerve; crural (leg) muscles and popliteus muscle 82

5 Arteries and accompanying vessels and nerves of the pelvic limb 84

6 Synovial structures of the pelvic limb (S REESE and K.-D BUDRAS) 86

Chapter 9: Head 1 Skull, including the hyoid apparatus 88

2 Skull, paranasal sinuses 90

3 Lymphatic system, superficial veins of the head, facial nerve (VII) 92

4 Facial muscles and mandibular muscles 94

5 Internal (deep) muscles of mastication, trigeminal nerve (V), mandibular nerve (V3), maxillary nerve (V2) 96

6 Lacrimal apparatus, optic nerve (II), ophthalmic nerve (V1), nerves and muscles of the eye, and external nose 98

7 Nose, larynx, oral cavity and pharynx .100

8 Pharyngeal muscles, cranial nerves of the vagus group (IX, X, XI), autonomic nervous system of the head, arteries of the head, external acoustic meatus 102

9 Tongue, lingual muscles, hypoglossal nerve (XII), salivary glands, and dentition 104

10.Joints of the head (S REESE and K.-D BUDRAS) 106

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Chapter 10: Central Nervous System

1 Spinal cord and meninges 108

2 Brain (Encephalon) and its meningeal coverings 110

3 Cerebrum (Telencephalon), brain stem and limbic system 112

4 Rhinencephalon, sites of egression of the cranial nerves, arterial supply of the brain .114

5 Cerebral veins, sinuses of the dura mater, cerebral ventricles and choroid plexuses 116

Chapter 11: Sense organs 1 The eye (P SIMOENS and K.-D BUDRAS) 118

2 The ear (H KÖNIG and K.-D BUDRAS) .120

3 Olfactory and gustatory (chemical) senses; superficial, deep, and visceral sensibility 122

Tables, Special Anatomy 1 Myology 124

2 Lymphology .134

3 Cranial nerves (C HERRMANN and K.-D BUDRAS) 136

General Anatomy 1 Osteology: membranous and chondral ossification; growth of bones in length and diameter .140

2 Osteology: structure and form of bone and cartilage 142

3 Arthrology: the connections of bones and the form of joints 144

4 Myology: general myology 146

5 Myology: skeletal musculature and its accessory structures 148

6 Nervous system 150

7 Endocrine system .152

8 Cardiovascular system (R HIRSCHBERG) 154

9 Lymphatic system (H.-G LIEBICH and K.-D BUDRAS) 156

10.Glands, mucous membranes, and serous membranes 158

Introduction to the physics of radiographic and ultrasound diagnostic techniques (C POULSENNAUTRUP) 160

Introduction to Computed Tomography and Anatomy of the CT Scan (C NÖLLER) 176

Contributions to Clinical and Functional Anatomy 180

Index 212

How to use this book:

The framed introductions at the beginning of the text-pages dealing with topographical anatomy give information with respect to the dis-section of the areas shown in the figures At the same time, they can be used as abbreviated disdis-section instructions Boldface terms of anatom-ical structures serve for emphasis and, insofar as they are identified by numbers, they are represented on the neighboring illustration-page where they are identified by the same number Numbers on the margin of the text-pages refer to the ‘Clinical and Functional Anatomy.’ The

numbers in the clinical anatomy part refer to the corresponding page in the topographical anatomy; e.g., ‘8.2’ refers to the part numbered

‘2’ on page 8 The anatomical/medical terms and expressions occurring in the text are explained and interpreted in ‘Anatomical Terms.’ Abbreviations of anatomical terms follow the abbreviations as employed in the Nomina Anatomica Veterinaria (2005) Other abbreviations are explained in the appertaining text, and in the titles and legends for the illustrations A few abbreviations that are not generally employed are listed here:

The cranial nerves (Nervi craniales) are designated with roman numerals I – XII

Spinal nerves (Nervi spinales):

n — Nervus spinalis

nd — Ramus dorsalis n spinalis

ndl — Ramus dorsolateralis

ndm — Ramus dorsomedialis

nv — Ramus ventralis

nvl — Ramus ventrolateralis

nvm — Ramus ventromedialis

nC — Nervus cervicalis (e.g., nC1 – first cervical nerve)

nCy — Nervus coccygeus s caudalis

nL — Nervus lumbalis

nS — Nervus sacralis

nT — Nervus thoracicus

Vertebrae

vC — Vertebra cervicalis (e.g., vC3 – third cervical vertebra)

vL — Vertebra lumbalis

vS — Vertebra sacralis

vT — Vertebra thoracica

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Preface to the Fifth Edition

The present revised and enlarged edition is published at a time of change,

which is characterized by the new appointment of all anatomically

orient-ed chairs in the German-speaking area The tendency to shorten the time

for anatomical education has existed for a longer time, which to a

moder-ate degree seems to be acceptable and unavoidable for the creation of free

space for new educational subjects Because this trend now seems to

assume excessive proportions, the danger exists of a partial or even total

renunciation of the dissection of the animal body, which since the time of

Leonardo da Vinci has been considered a very efficient and essential

method of deepening our knowledge The deficiency in practical exercises

cannot be compensated by our offer of anatomical drawings but will

miti-gate its negative impact Especially in the initial phase of the curriculum,

our realistic figures in the atlas part of our textbook have the indisputable

value that they provide the essential basis for understanding much used

sketches and schematic representations Beyond that, as an illustrated

guide to dissection, they promote the proper initiative for an independent

dissection and contribute by that to the acquisition of a solid knowledge For dissection and pictorial rendition, the topographical-anatomical pro-cedure offers the enormous advantage that comprehensive subjects can be imparted with brevity in a natural reality For the practicing veterinarian the topographical plates are suitable for orientation at surgical operations.The consideration of computed tomography, which thanks to Dr Nöller was integrated into the current eighth edition, has the objective to safe-guard an attractive field of activity for anatomy The imparting of normal structure discoverable by computed tomography and supplemented by the presentation of clinical-functional cases creates a solid basis for the further development and application of imaging procedures in the clinical curricu-lum and later in the practice of veterinary medicine

The Atlas of the Anatomy of the Dog was conceived as a compendium and

at the same time as an introduction to the topographical anatomical

dis-section as well as for teaching The subject matter of anatomy was

pre-pared from a topographical point of view with separation into systems To

do that, the osteology, myology, angiology, neurology and splanchnology

of the different parts of the body were dealt with in sequence in their

reci-procal re-lationship to one another and demonstrated by topographical

colored plates with complementary schematic diagrams The methods of

presentation emphasize the mutual topographical relationships of the

ves-sels and nerves considered, laying stress on their nomenclatural agreement

In that way, the concern for the multiplicity, the breadth, and the

com-plexity of the material should be minimized The concept chosen here, with

its close relationship of content and apposition of illustration and pertinent

description, has the advantage of being able to deal with the essential in the

smallest space

The present book offers to the students a clearly arranged illustrative

mate-rial and an abbreviated reading supplementing textbook study and

class-room material as well as an aid for review, especially for preparation

for examinations For the practising veterinarian, it is drawn up as a source

of quick information and to refresh and deepen what was previously

learned The breadth, division and sequence of the subject matter

accord-ing to the pre-cedaccord-ing are coordinated with the topographical dissection that

is offered to the students at the Free University of Berlin as the teaching

program in their first semester of study Upon the foundation achieved, the

subsequent study of comparative and clinically applied anatomy is

con-tin-ued Topographical anatomy is the foundation and the key to

understand-ing the associated medicine It is of special value to the surgeon and

pathol-ogist

Professor Fritz Preuss introduced the whole-animal topographical anatomy

in Berlin, and his dissection instructions directed the way for teaching up

to the dras-tinc shortening and repositioning of the dissection exercises The successful and exacting method of dissection with the short time avail-able places high demands on the students and requires a multisided support

by the instructors With its true to nature rendition of areas of dissection with accompanying text, the present atlas should serve for this purpose also Instructions for dissection of the illustrated preparation and guidance

to the person carrying out the exercise were placed at the beginning of the described part Structures to be dissected are specially emphasized in the text by boldface print To keep the space limitations, anatomical variations are given less attention The current Nomina Anatomica Veterinaria (HOLZHAUSEN, Vienna 1973) was utilized, which also holds in the main for the applied abbreviations Moreover, in the written material only ver-

tebrae and nerve branches were abbreviated (e.g.: VL 1 for the first lumbar

vertebra; nL 1vl for the ventrolateral branch of the first lumbar nerve) In the legends of the figures and the tabular compositions, owing to the limi-tations of space even more extensive, otherwise uncommon, abbreviations had to be used Suggestions and wishes of the students, for example with respect to preparing the tables for special myology and for anatomical terms were largely considered

Dissections from the anatomical collection of the Department of Anatomy, Histology and Embryology (Institute for Veterinary Anatomy, Histology and Embryology) of the Free University of Berlin served as models for the figures These specimens were prepared by the technical staff of the depart-ment, Mr Seifert, Mr Dressel, and Mr Schneider

Preface to the First German Edition (abridged)

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W B Saunders Comp., Philadelphia, London, TorontoHofer, M., 2000: CT-Kursbuch: Ein Arbeitsbuch für den Einstieg in dieComputertomographie 3 Aufl., Mattias Hofer Verlag Didamed Hyrtl, J., 1880: Onomatologia Anatomica Braunmüller, Wien International Committee on Gross Anatomical Nomenclature, 2005:Nomina Anatomica Veterinaria, 5 Ed., Nomina Histologica, 3 Ed., Ithaca, N Y

Kadletz, M., 1932: Anatomischer Atlas der Extremitätengelenke von Pferdund Hund Urban und Schwarzenberg, Berlin, Wien

Kealy, J K., 1991: Röntgendiagnostik bei Hund und Katze 2 Aufl., Enke,Stuttgart

King, A S., 1978: A Guide to the Physiological and Clinical Anatomy ofthe Thorax 4 Ed., Dept Vet Anat., University of Liverpool, Liver-pool

King, A S and V A Riley, 1980: A Guide to the Physiological and cal Anatomy of the Head 4 Ed., Dept Vet Anat., University of Liverpool, Liverpool L69 3BX

Clini-Koch, T und R Berg, 1981–1985: Lehrbuch der Veterinär-Anatomie Bd.1-3, Gustav Fischer, Jena

König, H E., 1992: Anatomie der Katze Gustav Fischer, Stuttgart, Jena,

Krstic, R V., 1984: Illustrated Encyclopedia of Human Histology Springer,Berlin, Heidelberg, New York, Tokyo

Krüger, G., 1968: Veterinärmedizinische Terminologie 3 Aufl., Hirzel,Leipzig

Leonhardt, H., 1990: Histologie, Zytologie und Mikroanatomie des schen 8 Aufl., Thieme, Stuttgart

Men-Liebich, H.-G., 2004: Funktionelle Histologie 4 Aufl., Schattauer, gart, N Y

Stutt-Lippert, H., 2006: Lehrbuch Anatomie 7 Aufl., Urban und Fischer, chen

Mün-Nickel, R., A Schummer und E Seiferle, 2003: Lehrbuch der Anatomie derHaustiere Gesamtausgabe, 5 Bd., Paul Parey, Berlin, Hamburg Nitschke, Th., 1970: Diaphragma pelvis, Clitoris und Vestibulum vaginaeder Hündin Anat Anz 127: 76-125

Nöller, C., 2006 : Klinisch-funktionelle Anatomie und phische Darstellung der Nase bei normo- und brachycephalen Kat-zen Diss med vet., Berlin

comptertomogra-Pierard, J., 1972: Anatomie Appliquee des Carnivores Domestiques, Chien

et Chat Sornabec, QuebecReese, S., 1995: Untersuchungen am intakten und rupturierten Lig crucia-tum craniale des Hundes Diss med vet., Berlin

Rohde, U, U Wiskott und H E König, 1980: Computertomographie desAbdomens beim Menschen und Hund – eine vergleichende Studie Kleintierpraxis 25: 135-142

Ruedorffer, N v., 1996: Morphologische Untersuchungen zur Orthologieund Pathologie der Tuberositas tibiae bei Hunden bis zum Alter von

2 Jahren Diss med vet., BerlinSalomon, F.-V und H Geyer, 2007: Atlas der angewandten Anatomie derHaustiere 3 erw Aufl., Enke, Stuttgart

Schaller, O., 1992: Illustrated Veterinary Anatomical Nomenclature Enke,Stuttgart

Schwarz, T, 2002: General principles in CT imaging planning The pean Association of Veterinary Diagnostic Imaging, Yearbook 2002,

Euro-S 9-23Simoens, P., 1985: Morphologic study of the vasculature in the orbit andeyeball of the pig Thesis Fakul Vet Med., State Univ GhentSuter, P F und B Kohn, 2006: Praktikum der Hundeklinik Begr v H G.Niemand, 10 Aufl., Paul Parey, Berlin, Hamburg

Wünsche, A und K.-D Budras, 1972: Der M cremaster externus resp

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Introduction to Anatomy

The term anatomy stems from the Greek word, ‘anatemnein’ which means

to dissect, to cut apart The important anatomist Hyrtl spoke consistently

also of the art of dissection The original meaning is true even today;

although the term has gained a wider meaning Modern anatomy is not

limited to mere description but emphasizes the interrelations between form

and function as well as the application of anatomical knowledge in the

clin-ic Then as today the student gains most of his knowledge by dissection of

the animal body in the laboratory, where he lays bare the ‘naked truth’

(Nudas veritas) This practice also serves to obtain a necessary

finger-dex-terity, which in later professional life, in the first place in surgery, is of

immeasurable value Beyond that there are hardly any limits to

investiga-tion by enthusiastic dissecinvestiga-tion Even the very best anatomical collecinvestiga-tion of

outstanding demonstration-dissections cannot replace practical work in

the laboratory, but can however indeed make it easier and more efficient

The thorough study of anatomical preparations is indispensable like the

industrious use of textbooks and atlases All of these aids are more

impor-tant today than ever since there is much less time available for practical

work in the laboratory than formerly Shortening the teaching time

allot-ted to anatomy in favor of newer disciplines was unavoidable

Anatomical study is, unlike any other basic discipline, important in

learn-ing the language of medicine, the terminology Many terms for diseases and

methods of treatment have their origin in anatomical terms Centuries-long

research and description brought an unforeseen abundance of synonyms

The function of the international nomenclature commission has been to

thin out the jungle of terms and to publish a recognized list of official terms

with useful synonyms

In its entirety, anatomy is subdivided into macroscopic (gross) anatomy,

microscopic anatomy and developmental anatomy However, the areas of

anatomy flow together without boundary, forming a unit, an

understand-ing constantly and forcefully advocated by the important Berlin veterinary

anatomist and, at an earlier time, the professorial chair of our department,

Professor Preuss The oldest and most encompassing area is macroscopic

anatomy, often placed equal to the term anatomy Where the accessories to

observation in macroscopic anatomy, the bare eye and the dissection hand

lens no longer reach, it passes over into the area of microscopic anatomy

(histology and cytology), to which the microscope serves as accessory The

boundary between macroscopic and microscopic anatomy is also called

mesoscopy, which is gaining more and more in significance The latter area

deals with the same material and pursues the same goals; it is only the

tech-nique that is different The third area, embryology, is concerned with

onto-genesis (development of the individual) before and after birth and, in

addi-tion to embryological methods, applies also macroscopic, microscopic and

mesoscopic methods

Like the remaining disciplines, macroscopic anatomy can be presented

from different points of view with emphasis on special areas of greater

dif-ficulty In so doing, the basic facts remain of course unchanged

Systematic, descriptive anatomy describes the animal body with all its parts

as systems of structure and organ-systems, strictly divided from one

anoth-er and thanoth-erefore without attention to their natural intanoth-erdependence

Expan-sive descriptions treat many particulars and allow some-times the view to

the important to be missed; nevertheless they are a necessary prerequisite

to the remaining, subsequent kinds of observations to which the

descrip-tive anatomy has led

Systematic anatomy can be subdivided further into general and special

anatomy

General anatomy treats of facts that are generally valid for the entire

sys-tem of structure or the organ-syssys-tem

Special anatomy provides special data for these structure- and

organ-sys-tems that hold for individual structures, as for one bone

Comparative anatomy emphasizes anatomical correlations, similarities

and variations between the individual animal species and human beings

Comparisons of anatomy between the individual species are very often

informative and helpful for homology and determining the function of

anatomical structure Already Goethe utilized principles of comparative

anatomy to good advantage with the discovery of the incisive bone of

human beings This bone occurs regularly in our domestic animals and

only occasionally in human beings With his study of the human skull he encountered a specimen with a developed incisive bone It was by compar-ison with the animal skull that he was able to identify the bone and estab-lish its homology

Topographical anatomy emphasizes the varying position-relationship of

anatomical structures and underlines the areas of application for clinical medicine The relationship of anatomical structures is analyzed step

by step and in doing so the whole structural plan of the body is regarded

Applied anatomy is directed clinically and emphasizes the relationship of

anatomical structures from which treatments or diseases of animals can be determined or explained In that way not only interdisciplinary coopera-tion and interest for the veterinary profession are promoted but also the learning of anatomy is made easier

The anatomy of the living dog is undoubtedly a significant part of the

whole of anatomy It presents the body in its natural condition In that way

a significant completion and an adjustment for unavoidable disadvantage becomes imperative in the remaining subjects of the whole of anatomy, which must tolerate postmortem changes such as variations in color, con-sistency and character as well as artificial changes resulting from fixation Anatomy of the living dog cannot be given attention here for several rea-sons It is adaped even less for rendering in a book, but can be offered to the students better and more successfully in an exercise under the instruc-tion of a clinically experienced anatomist

Radiographic anatomy and sonography are directly connected to the

clin-ic In the teaching of anatomy, the first experiences are obtained in sis of radiographs of the normal animal body This experience will be uti-lized and considerably supplemented in the total associated area of study Presentations of abnormal or even pathological changes should awaken the interest and accordingly add ‘spice’ to the teaching of anatomy

analy-The atlas of anatomy presented here is adapted in special measure to

signif-icantly combine and coordinate the different methods of presenting

anato-my and the manner of viewing it The textual part can be presented in a very compressed form since the different anatomical circumstances can be

‘read off’ from time to time from the adjacent color-plate Beyond that, a good topographical color-plate presents an ideal introduction for topo-graphical dissection, which is then completed only by brief remarks Also the requisites of comparative veterinary anatomy are taken into account in this atlas insofar as the simply structured (from many points of view) canine body is set out as the ‘cornerstone.’ Building upon this knowledge, the more complicated (from many points of view) anatomy of the remain-ing domestic animals can be comprehended from the aspect of comparative anatomy

Art and anatomy with their mutual interrelations are forcefully impressed

on us with each visit to a museum The artist is inspired by the corporeal beauty, and teachers and students of anatomy enjoy and profit from the tal-ent and painstaking detail in the artistic presentation Gifted with genius were realized the claims of Leonardo da Vinci, whose abundant anatomi-cal drawings came about after basic studies of anatomy Aristotle published among other things an anatomical description of senile sexual reversal in the bird as well of the horse hoof in regard to founder What fascination of anatomy passes over to art, Rembrandt immortalized in his work ‘The anatomy lesson of Dr Nicolaes Tulp.’ The greats of world history gifted with genius like Aristotle, Leonardo da Vinci and Goethe show proof of their enthusiasm for anatomy with anatomical illustrations, descriptions and research results To Goethe’s credit was the promotion of educational art and the introduction of plastic wax models in Germany, to which he, himself, was inspired during his journey to Italy, especially in Florence The good qualities of wax models, which is true to an equal measure for well done true-to-nature illustrations, Goethe expressed in his novel ‘Wilhelm Meisters Wanderjahre’ with the following excellent formulation: ‘If you concede that most physicians and surgeons retain in their minds only a gen-eral impression of the dissected human body and believe that to satisfy the purpose; so such models will certainly suffice, which refresh in his mind again little by little pictures that are fading and actively retain for him just the necessary.’ His investigative mind held Goethe, who with his discovery

of the human incisive bone felt ‘unspeakable joy.’

Trang 9

a) S UBDIVISION OF THE B ODY

The longitudinal lines and planes of the body are useful for the orientation

of the body and of the body surface The dorsal (a) and ventral midline (b)

are the dorsal and ventral median lines of the body, respectively

The median plane (A) is the plane between the two lines mentioned above

It divides the body into right and left halves Sagittal (paramedian) planes

(B) are adjacent planes parallel and lateral to the median plane They divide

the body longitudinally, but into unequal parts Transverse planes (C) are

planes that divide the body transversely and are perpendicular to the

medi-an medi-and sagittal plmedi-anes Dorsal plmedi-anes (D) lie parallel to the dorsal body

sur-face They divide the body perpendicular to the longitudinal (median and

paramedian planes) and transverse planes In that view, two symmetrical

body sides appear and it is for that reason that dorsal planes are also called

bilateral planes

b) T ERMS THAT D ESCRIBE THE D IRECTION AND T OPOGRAPHICAL R ELATIONS OF

O RGANS derive partially from body parts, e.g., in direction toward the tail

(caudal — c), partially from landmarks of the body surface, e.g., parallel to

the median plane (sagittal —d) or designate with respect to hollow organs

external or internal Furthermore terms are used as left (sinister) and right

(dexter), short (brevis) and long (longus) or deep (profundus) and

superfi-cial (superfisuperfi-cialis), longitudinal (longitudinalis) or transverse (transversus)

as well as lateral (lateralis) and toward the median plane (medialis) The

term cranial (e), in a direction toward the head, cannot be applied in the

head region Here the term rostral is used (f, in a direction toward the tip

of the nose) The term dorsal (g) relates to the ‘back’ or dorsum of the body

It may also be used with respect to the proximal parts of the limbs; but has

Topographical Anatomy

Chapter 1: Surface of the Body and Axial Skeleton

1 Division of the animal body

a different meaning on the limb extremities The term ventral, in a

direc-tion toward the belly (venter), may be used on the proximal parts of the

limb, but is not used on the free part of the limbs The terms proximal (i, toward the attached end) and distal (m, toward the free end) are related to

the axis of the body (vertebral column and spinal cord with the origin of

spinal nerves) On the limbs, from the carpus distally, the term palmar (l,

the surface of the manus that faces caudally in the normal standing

atti-tude) is employed; from the tarsus distally (m, the surface of the pes that faces caudally in the normal standing attitude of the animal), the term plan-

tar The term dorsal is utilized alike on the thoracic limb from the carpus

distally and on the pelvic limb from the tarsus distally It refers to surface

of the manus and pes that is cranial in the normal standing attitude of the

animal Terms like abaxial (n, away from the axis) and axial (o, toward the

axis) are related to the central axis of the hand (manus) or foot (pes), in which the axis lies between the third and fourth digits In front (anterior), behind (posterior), above (superior) and below (inferior) are terms often used in human anatomy and refer to the human body in the normal upright attitude To avoid misunderstanding, these terms are not applied to the quadruped animal body Their use in veterinary anatomy is restricted to

certain areas of the head; e.g., upper and lower eyelids, anterior and

pos-terior surfaces of the eye

c) P ARTS OF THE B ODY AND B ODY R EGIONS subdivide the body, including the surface of the body Parts of the body are head and trunk with neck, rump, and tail, as well as the limbs The body regions divide the surface of the body and can be subdivided into subregions In the latter case, they appear indented in the following table

Regions of the cranium

6' Dorsal nasal region

6'' Lateral nasal region

6''' Region of the naris

7 Oral region

7' Superior labial region

7'' Inferior labial region

Regions of the neck

18 Dorsal neck region

19 Lateral neck region

Regions of the dorsum

23 Thoracic vertebral region 23' Interscapular region

Regions of the abdomen

30 Cranial abdominal region 30' Hypochondriac region 30'' Xiphoid region

31 Middle abdominal region 31' Lateral abdominal region

37 Region of the tuber ischiadicum

38 Caudal region (tail region)38' Region of the root of the tail

39 Perineal region39' Anal region39'' Urogenital region

40 Scrotal region

Regions of the thoracic limb

41 Region of the humeral joint

42 Axillary region 42' Axillary fossa

Regions of the pelvic limb

51 Region of the hip joint

52 Region of the thigh

53 Genual region (region of the knee, region of the stifle joint) 53' Patellar region

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d 32

9 12101311

6'9'

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6 6'' 14

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23 g 24

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a

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3338'

52

41 44

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kg

555756

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b

20513

16 1915

22' 22 22''21

1787''14

b

6'''7'

25

26

42

49 5048

47

43

292630''

42'28

5855

545353'

g59k

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2 The Skin (Common Integument)

lay-ers: I an epithelial layer designated epidermis and II a connective tissue

layer designated dermis or corium The dermis rests upon an underlying

layer of connective tissue, the subcutaneous layer or subcutis (Tela

subcu-tanea) The latter consists of a fatty part, the panniculus adiposus, and a

supporting fibrous part that, together, constitute the superficial fascia

I The epidermis (1) is made up of a stratified squamous epithelium that is

cornified (keratinized) at its surface Thickness and degree of keratinization

depend on the mechanical stress to which this layer is subject The

epider-mis is composed of a deep, still living, layer, (stratum germinativum = basal

layer, —27) which, by mitotic division, furnishes cell replacement, a

spin-ous layer (26), a cornifying, dying layer (stratum granulosum, —25) as well

as cornified cell layers, stratum lucidum (24) and stratum corneum (23) In

addition to the epidermal cells, there are melanocytes, LANGERHANS’

cells, and MERKEL’S tactile discs, especially in the stratum germinativum

‘Horn’ is cornified epidermis and is of varying quality in the different

regions of the body On the pads and in other regions of the skin there is

soft horn Hard horn is found at the claw In the skin and at the pads, the

cornified cells are shed as scales owing to reduced adhesion of membrane

coating materials At the same time, because of good adhesion as a solid

mass, the horn of the claws remains restored by distal growth conical The

individual horn cell of the claw is distinctly harder than that of the skin In

areas where soft horn is formed, the epidermis exhibits a stratum

granulo-sum between the stratum spinogranulo-sum and the cornified layers The stratum

granulosum is so-named because of the keratohyalin granules that it

con-tains The proteins within this layer of cells coat and ‘glue’ the keratin

fil-aments together At individual sites additionally a stratum lucidum occurs

It consists of young, not yet differentiated, cornifying cells, the cytoplasm

of which appears somewhat transparent when examined under the

micro-scope, hence the name stratum lucidum In the areas of formation of hard

horn, these layers are absent, so that the cells of the stratum spinosum

cornify directly without intervening strata granulosum and lucidum

The function of the epidermis consists of the replacement of cornified cells

as a protection from radiation (radiation absorbing pigments; see

histol-ogy), from the loss and entrance of water into the body, from the entrance

of parasites and for protection against trauma With traumatic injury to the

skin, healing is furthered by covering the exposed dermis by epidermal cells

as soon as possible

II The dermis or corium (6) consists of a thin, loosely arranged papillary

layer (2), the papillae of which are seated in corresponding depressions of

the epidermis, and a dense reticular layer (7) The papillary layer contains

mainly loosely arranged collagenous fibrils The reticular layer consists of

a plexus of coarse nondistensible collagenic fibers with a predominant

course direction Elastic fibers are present in both layers and function to

restore the typical texture of the tissue following lacerations or other

dis-tortion of the skin (with respect to the cells that are found here, especially

fibrocytes, fibroblasts, mast cells, plasma cells, macrophages and pigment

cells, see histology)

The subcutis (10) (Tela subcutanea) consists mainly of loose connective

and adipose tissue It is penetrated by connective tissue cords that fix the

skin to the underlying fascia or periosteum The panniculus adiposus is the

layer of fat tissue within the subcutis

Functionally, the subcutis with its subcutaneous fat tissue serves as a

cush-ioning tissue, serves for the storage of calories and water as well as

ther-moregulation Its loose connective tissue functions as a gliding layer Where

the subcutis is lacking (lips, cheeks, and eyelids) this gliding function is

lacking and the striated musculature ends here directly in the dermis

The blood supply of the skin is provided by larger arteries and veins of the

subcutis that, owing to the mobility of the skin, have a tortuous course

They send branches to the dermis that form here two networks The

arter-ial network of the dermis (9) is located at the boundary with the subcutis

and the subpapillary network (3) lies between the papillary and reticular

layers and gives off subepidermal capillary loops into the papillary body

The corresponding venous plexuses have a comparable location A further

subfascial vascular plexus joins the blood supply of the subcutis The blood

flow can be cut short by arteriovenous anastomoses (4), thus avoiding the

capillary bed, and in this way the vascularization of the skin is regulated

The papillary layer is especially well supplied with blood These vessels

dilate in order to give off heat and constrict to conserve body temperature

In this way they function like the sweat glands in thermoregulation The

venous plexuses also function as a place to store blood

The lymphatic supply is by lymph capillary networks that begin

subepi-dermally and invest the hair follicles and skin glands

The nerve supply is by sensory and sympathetic neurons (sympathetic

nerve plexuses invest the blood vessels and function to regulate the blood pressure and in thermoregulation) The skin can be considered as the

largest sensory organ of the body Numerous nerve terminals (16) and

ter-minal end corpuscles (e.g., MEISSNER’S tactile discs, —17, and

VATER-PACINIAN lamellar corpuscles, —22) serve as receptors for sensory

stim-uli With loss of their myelin sheaths, free nerve endings penetrate the dermis at particular sites of the body and serve to mediate the sensation of pain

epi-b) The H AIRS cover nearly the entire body surface, except the planum

nasale, anus, vulvar lips and limb pads Hairs are cornified filiform

struc-tures that are formed by the skin The hair is subdivided into the shaft (15), which projects beyond the surface of the skin, the root (21), which is

obliquely oriented within the dermis and has at its proximal end an

expanded part, the hair bulb (8) Hair root and hair bulb are in a divided

epithelial root sheath (Vagina epithelialis radicularis) The outer part of the

sheath is continuous with the superficial epidermis Its inner part cornifies

above the mouth of the sebaceous gland (18) and will be shed The

con-nective tissue root sheath (Vagina dermalis radicularis) is continuous with

the surrounding connective tissue The epidermal and dermal root sheaths together with the bulb of the hair constitute the hair follicle The parts of

the hair are medulla (12), the cortex (13) and the superficial hair cuticle

(14), which consists of thin scale-like cornified cells and, the same as the

medulla, is used for forensic species identification and individual

diagnos-tic procedures The arrector pili muscle (5) terminates below the mouth of

the sebaceous gland, attaching obliquely to the dermal sheath of the root

of the hair Its contraction results in erection of the hair (in human beings, this brings about the phenomenon of ‘goose pimples’) Contraction of the arrector pili muscle compresses the sebaceous glands and, in erecting the hair, increases the air space between the hairs and the skin surface for ther-mo-isolation

The hair coat depends on the breed and is characterized by the individual

and group-like arrangement of the hairs, the different portions of the vidual hair types (lead hairs, guard hairs, wool hairs) as well as by the den-sity, length and color of the hairs There are basically three types of hairs:

indi-The ‘lead’ hair or ‘main’ hair is long, stiff, and slightly curved It is pendent of other hairs and in the dog occurs only rarely Guard hairs are

inde-shorter than the lead hair, arched near the tip and thickened Both lead and

guard hair types form the hair coat (Capilli) The third and shortest type of

hair is the wool hair It is very thin, pliable and in its course slightly or strongly undulated Guard and wool hairs pass in a bundle or tuft togeth-

er from a compound hair follicle, in which case one guard hair is rounded by the six to twelve wool hairs that accompany it

sur-The wool hairs (11) predominate in the coat of the puppy In most canine

breeds they lie under the hair coat and only in a few breeds such as the Puli and Commodore, do they project above the hair coat and form a superfi-cial ‘wool coat.’

Sinus or tactile hairs (19) are remarkably long, special forms of hair in the

vicinity of the opening of the mouth (Rima oris) To receive tactile stimuli,

the root of the hair is ensheathed by a blood sinus (20) that is contacted by

numerous sensory nerve endings Owing to the great lever action of this long hair even the finest tactile stimuli result in stimulation of this receptor The length of the hairs varies considerably and is dependent on breed In the ancestors of the dog, who lived in the wild, the longest hairs are found

on the dorsum and the shorter ones on the belly and head But this pattern

is mostly lost with domestication In wild Canidae, the thickness of the hairs increases toward the belly (thickness is about 0.1 mm) The color of the hair is effected by the melanin content of the cornified cells as well as the inter- and intracellular air bubbles, especially of the medullary cells

The direction of the hairs characterizes the coat That part of the coat in

which the hairs have a uniform direction is called the Flumina pilorum In

a vortex, the hairs are arranged divergently or convergently with respect to

a central point By the crossing of converging lines of hairs, hair ‘crosses’ are formed

Trang 12

88

8

h

gf

dca

b

ee

Epidermis Common integument

Epidermis of digital pad Epidermis of wall of claw

Legend:

a Intrapapillary capillary loop

b Apocrine sweat gland

c Elastic fiber

d Collagenic fiber

e Unilocular adipocyte

f Dermal root sheath

g Epithelial root sheath

h Hair papilla

Fibrous layer

Panniculus adiposus

10 Subcutis

9 Arterial network and venous

plexus of the dermis

Trang 13

subcutis and fix the pad to the underlying fascia and to the skeleton

Well-developed connective tissue bands (Tractus tori —15) are present in the

metacarpal and metatarsal pads They fix the pads proximally to the metacarpal or metatarsal bones, respectively The dermis has very firm con-nective tissue bundles and forms a very high papillary body with conical papillae The epidermis of the pad is up to 2 mm in thickness and forms cor-responding depressions in the soft horn (soft cornified epidermis) The pads are richly supplied with blood and lymph vessels as well as nerves

3 Cutaneous Glands, Modifications of the Skin, Digital End-organs

the mammary gland, which is a modified sweat gland

I The sebaceous glands (see p 4) open into the hair follicles and are

pre-sent at a few sites of the body independent of the presence of hairs as at the

transition of the skin to the cutaneous mucous membrane (lips, anus)

Sebaceous glands are lobular The peripheral cells have a high rate of

mito-sis and the daughter cells are pushed centrally to the lumen of the gland

Here the enlarged and aging cells break down (holocrine secretion) and the

sebum thus liberated reaches the lumen of the gland It passes by way of a

short excretory duct to the lumen of the hair follicle and thus to the skin

Sebum makes the skin soft and pliable and gives the hairs a natural sheen

II The sweat or sudoriferous glands are classified as merocrine (eccrine)

and apocrine glands (odor glands) This classification was based on a

sup-posed apocrine secretion of the (apocrine) odor glands; however, this was

subsequently disproven Both types of sweat glands secrete according to the

merocrine (eccrine) manner of secretion (see histology)

The merocrine sweat glands are usually coiled, unbranched, tubular

glands They occur in the dog only on the pads of the limbs (see below;

some authors consider these glands to be apocrine sweat glands) In human

beings, real merocrine (eccrine) sweat glands are present in large areas of

the skin surface

Apocrine sweat glands or odor glands (see p 4) are present over wide areas

of the skin surface, but they are comparatively underdeveloped These

tubular glands open usually into the hair follicle Their thick secretion has

an alkaline reaction and is responsible for the individual species odor In

man, the glands are well developed but limited to a few regions of the body:

anus, vulva, axilla

III Special modifications of the skin occur as the glands of the external

acoustic meatus, the circumanal glands, glands of the paranal sinus (‘anal

sac’) and glands of the dorsal tail organ, glands of the eyelids and the

mam-mary glands

The ceruminal glands of the external acoustic meatus are mainly sebaceous

glands with fewer apocrine sweat glands Their brown, oily secretion is

called cerumen

The circumanal glands surround the anus in the hairless or nearly hairless

region of the anal cutaneous area In the dog, we are dealing with modified

sebaceous glands; in other domesticated animals, with modified apocrine

sweat glands Superficially located individual glands open into the hair

fol-licles Deep glands are also called hepatoid glands as their secretory cells

appear similar to hepatocytes The glands lack an excretory duct and their

function is unclear

The glands of the wall of the paranal sinus (see clinical-functional

anato-my, 56.5) are apocrine sweat glands and sebaceous glands The paranal

sinus is commonly termed the ‘anal sac.’

The dorsal caudal (tail) organ is composed of sebaceous and apocrine

glands and is described more fully in the clinical-functional anatomy (6.5)

Glands of the eyelids are described in the clinical-functional anatomy (see

also 118.1)

Mammary gland; see p 32.

b) S KIN M ODIFICATIONS are the nasal plane and the limb pads: carpal pad,

metacarpal/metatarsal pad, digital pads

I The nasal plane (see p 98), depending on breed, varies from

unpigment-ed to its being strongly pigmentunpigment-ed The dermis forms distinct papillae The

epidermis is strikingly thin, and its superficial, cornified layer (stratum

corneum) consists of hard ‘horn’ (hard cornified epidermis) that exhibits a

polygonal pattern The surface pattern is individually specific and for this

reason serves to identify the individual animal Glands are absent The nose

of the dog is kept moist by lacrimal fluid (see p 98) and the secretion of the

lateral nasal gland, which is located deeply in the maxillary recess of the

nasal cavity The evaporation of the fluid lowers the temperature of the nasal

plane, which ordinarily feels cold to the touch (hence the saying, ‘cold as a

dog’s nose’)

II The pads of the dog are the digital pads (14) at the level of the distal

inter-phalangeal joints, the metacarpal (13) or metatarsal pad at the level of the

metacarpophalangeal and metatarsophalangeal joints and the carpal pad

(12) that is laterodistal at the carpus The thick subcutis of the pads has

much fat tissue and contains sweat glands It is subdi vided into

compart-ments by radiating strands of collagenous and elastic fibers and is very

sen-sitive (painful) if swollen due to increased tissue pressure when inflamed

The connective tissue strands radiate from the dermis of the pad into the

c) The D IGITAL E ND - ORGAN is the bony end of the digit invested by a highly modified cutis (skin) Except for the digital pad, a subcutis is lacking The dermis is developed in the form of papillae, villi or laminae or it has a smooth surface The inner surface of the epidermis has a corresponding configuration: depressions that seat the papillae and villi, narrow furrows adaped to the laminae, or a smooth surface where it contacts the smooth surface of the dermis

The cornified epidermis of the claw (Unguicula) is conical in form and invests the unguicular process (11) Dermis and epidermis are segmentally

similarly differentiated as on the fingernail of the human being and on the equine hoof Both, dermis and epidermis, are adapted to one another like the patrix (stamp = dermis) to the matrix (impression = epidermis)

The bony unguicular crest is overlain basally by a prominence of the skin,

the vallum (7) The external lamina of the vallum is haired; the unhaired

inner lamella is comparable to the limbus (periople) of the horse It forms

a soft horn (Eponychium, —1) over the hard cornified epidermis of the

claw The eponychium corresponds to the periople of the horse and, like the periople, is worn off far proximal to the distal end of the claw (On the human fingernail, the soft eponychium is removed at the manicure.)

In the depth of the unguicular groove is the fold that corresponds to the

coronary part of the equine hoof Its dermis bears papillae (10) Its ing epidermis produces a tubular horn that, as a mesonychium (2), pro-

cover-vides a considerable part of the claw Dorsal on the unguicular process

there is a smooth dorsal swelling of the dermis (Dorsum dermale —8), that

is particular to the digital end-organ of the dog and that, according to our investigations, is not comparable to the coronary part of the equine hoof

On the epidermis covering it, the dorsal horn of the wall (dorsal hypo

-nychium —3) is formed In the lateral region of the unguicular process

lamellae are present, dermal lamellae (9) and correspondingly formed cornified epidermal lamellae that form the lateral wall horn (Hyponychi-

non-um laterale, —4), which is simply layered and forms the internal lining of

the conical claw horn

Palmar (plantar) on the unguicular process is the solear part on which the

dermis bears distinct villi Here, tubular solear horn (5) is formed, the cells

of which undergo substantial desquamation

Around the tip of the unguicular process there is present a soft terminal

horn (Hyponychium terminale, —6) that fills out the distal part of the

con-ical claw horn and serves thus as a ‘filling’ horn

Trang 14

1

2

3 4

5

8 910

1011

Claw and digital pad

Subcutaneous tissue of pad:

16 Retinacula

17 Panniculus adiposus (Fat pad)

(cross section)

Trang 15

a) The V ERTEBRAL C OLUMNencloses and protects the spinal cord It has a

sup-porting function with respect to the statics and dynamics of the animal’s

body For that, stability is assured by the individual vertebrae, and elasticity

as well as pliability by the intervertebral symphyses and the vertebral joints

The vertebral column consists of seven cervical vertebrae (vC 1 – 7),

thir-teen thoracic (vT 1 – 13), seven lumbar (vL 1 – 7), three sacral (vS 1 – 3),

which are fused to form the sacrum, and about twenty caudal (coccygeal)

vertebrae (vCy 1 – 20)

I The vertebrae (see text-illustration) consist of three basic constituents:

body and its parts, arch and processes, that are modified in different ways

according to the functional requirements of the particular region

The body of the vertebra (1) has a ventral crest (2), (distinct in the region

of the cervical vertebral column) and cranial (3) and caudal (4) extremities

On the thoracic vertebrae, both the caudal (5) and cranial costal foveae (6)

form a common articular facet for the head (Capitulum) of the rib (see

below) The vertebral foramen (7) is the space enclosed by the body and

arch The vertebral canal is formed by the serial vertebral foramina and the

soft tissues extending between adjacent vertebral arches and bodies It

con-tains the spinal cord with its cauda equina

The arch of the vertebra (8) is made up of a pedicle basally and a flattened

lamina dorsally The intervertebral foramina (9) are bounded by the cranial

(10) and caudal (11) vertebral notches of the vertebra of the same and

pre-ceding segments Excepting the first cervical nerve (see below), these

foramina are passages for the spinal nerves

Of the processes of the vertebrae, the spinous process (12) is most distinct

(exceptions are the first cervical vertebra and the caudal vertebrae) The

transverse processes (13) are well developed on the cervical and lumbar

vertebrae On the thoracic vertebrae, they have a costal fovea (14) that

bears an articular facet for the costal tubercle (see below) From the first to

the sixth cervical vertebrae there are transverse foramina (15) at the base

of the transverse processes, which altogether form the transverse canal that

transmits the vertebral artery, vein and nerve The cranial articular

process-es (16) and the caudal articular procprocess-essprocess-es (17) form synovial joints between

the vertebrae A costal process (18) is present on the 3rd – 6th cervical

ver-tebrae as the ventrocranial extremity of the transverse process, which is

bifurcate in this region In the lumbar vertebral column the ends of the

transverse processes represent costal processes that are remnants of the

ribs, and can develop to form lumbar ‘ribs.’ An accessory process (19) is

lacking or poorly developed in the caudal part of the lumbar vertebral

col-umn In the cranial lumbar region it is developed as an independent

process At the transition to the thoracic vertebral column, it passes onto

the caudal contour of the transverse process and no longer stands

inde-pendently The mamillary process (20) of the lumbar vertebrae is expressed

on the cranial articular process (mamiloarticular process) and changes its

position at the transition to the thoracic vertebral column, passing onto the

transverse process, actually to the cranial contour of the transverse process

Hemal processes (21) are developed from the 4th caudal vertebra and

become gradually indistinct caudally On the 4th to the 7th or 8th caudal

ver-tebra, they may unite to form a hemal arch (22).

The interarcuate spaces are dorsal and, in life, closed off by the

interarcu-ate ligaments The lumbosacral space (23) and the sacrococcygeal

(sacro-caudal) space (24) are especially wide and of significance in performing

epidural anesthesia The atlanto-occipital space is suitable for tapping the

subarachnoid space, which is filled with cerebrospinal fluid

Special features are present on the following cervical vertebrae: The first

cervical vertebra (atlas, —25) has a broad-surfaced lateral process (26), also

designated the wing of the atlas (Ala atlantis) The alar notch (27) calar

foramen of other domestic mammals) is cranial at the attachment of the

wing of the atlas to the lateral mass (see below) and is occupied by the

ven-tral branch of the first cervical nerve Contrary to the other spinal nerves,

the first cervical nerve does not exit the vertebral canal by an intervertebral

foramen but by the lateral vertebral foramen (28) The vertebral foramen

of the atlas is also different in that it is bounded dorsally by a dorsal arch

(29), ventrally by a ventral arch (30) The two arches are joined laterally by

bone designated the lateral mass (Massa lateralis) The atlas is the only

ver-tebra to have a ventral arch (30) in the place of the body This is due to the

caudal shift of a great part of the embryonal primordium of its vertebral

body to form the dens of the axis The second cervical vertebra, the axis

(31), for this reason contains in its dens (32) the displaced part of the body

of the atlas The last cervical vertebra differs from the other cervical vertebra

by its large spinous process, its caudal costal foveae for the first ribs and by the absence of the transverse foramen

4 Vertebral Column and Thorax

The vertebrae are studied individually and on the mounted skeleton to obtain a total overview of the normal S-shaped curvature with its lordoses (ventral convexities) and kyphoses (ventral concavities) From a forensic view, particular attention is placed on the identification of individual vertebrae, for which reason comparison of the different segments of the vertebral column is done

II The sacrum is formed by the fusion of the three sacral vertebrae ally, it bears the sacral wing (33), whose auricular surface (34) forms a syn- ovial joint with the auricular surface of the ilium The median sacral crest

Later-(35) is formed by an incomplete fusion of the spinous processes The

later-al ends of the fused laterlater-al (transverse) processes form the laterlater-al sacrlater-al

crest (36) The intermediate sacral crest (37) results from the sequential

arrangement of the fused mamilloarticular processes The promontory (38)

forms the cranioventral contour of the sacral bone and takes part in the limiting terminal line of the pelvic inlet From the vertebral canal, the sacral nerves enter intervertebral foramina and leave the vertebral column after

dividing into dorsal and ventral branches that emerge from the dorsal (39)

and ventral sacral foramina (40), respectively, that proceed from each

inter-vertebral foramen

(41), connected to the sternum by synovial articulation Ribs 10 – 12 are

the freely moveable, ‘breathing’ asternal ribs (42) By the overlapping of

the cartilaginous parts of the asternal ribs, a costal arch is formed on both sides of the body The last rib does not regularly participate in the forma-tion of the arch It usually terminates freely in the musculature of the

abdominal wall as a ‘floating’ rib (43) Ribs, sternum and thoracic

verte-bral column form the thorax, the inlet of which is bounded by the first pair of ribs and the outlet by the costal arches The dorsal part of the rib

is osseous (Os costae, —44) Its head (45) bears cranial and caudal

artic-ular facets (46) The two articartic-ular facets are separated by a rough crest

that, in most ribs, is indirectly in contact with the intervertebral disc by means of the intercapital ligament (see illustration, p 11) An indistinct

neck of the rib (47) connects the head to the body of the rib (48) The

prox-imodorsally located costal tubercle (49) bears an articular surface (50) for articulation with the costal fovea of the transverse process The angle of

the rib (51) is only indistinctly recognizable The costal cartilage (52)

begins at the costochondral junction and, slightly distal to this, there is a

distinct bend, the knee of the rib (53) that in other domestic mammals is

in the area of the costochondral junction

(55) with its six sternebrae (56), and the xiphoid process (57), which is

bony cranially, cartilaginous caudally The first pair of ribs articulates with the manubrium, the second at the synchondrosis that joins the manubrium

to the body of the sternum, the third through the seventh at the following sternal synchondroses, and the eighth and ninth jointly at the synchondro-sis joining the body to the xiphoid process

8 74

7 3

Trang 16

43 4241

12

2116

15131110

8

26

2517

32

31

302827

15

29

31

1213

54

3

12173

12

15

1313

18

1616

4

765

161718

54

14131211109

57

55

56

5352

4448

5145

4946

4750

201918=131817

3338

171913

1220

12

146

16

1013

111917

16

2417

37

39363534

2312

16

3716

2237

1617

40

211313

Caudal costal fovea (5)

Cranial costal fovea (6)

Vertebral canal (7)

Vertebral arch (8)

Intervertebral foramen (9)

Cranial vertebral notch (10)

Caudal vertebral notch (11)

Spinous process (12)

Transverse process (13)

Costal fovea (14)

Transverse foramen (15)

Cranial articular process (16)

Caudal articular process (17)

Median sacral crest (35)

Lateral sacral crest (36)

Intermediate sacral crest (37)

Promontory (38)

Dorsal sacral foramen (39)

Ventral sacral foramen (40)

(lateral view)

Trang 17

b) L IGAMENTS OF THE V ERTEBRAL C OLUMN

Three ligaments extend over longer areas of the vertebral column Short

ligaments bridge over the space between individual vertebrae

The ventral longitudinal ligament is attached ventrally to the bodies of the

vertebrae and to the intervertebral discs It extends from the second

cervi-cal vertebra to the sacrum

The dorsal longitudinal ligament lies on the floor of the vertebral canal and

attaches at the dorsal border of the intervertebral disc It extends from the

axis to the first caudal vertebrae

The nuchal ligament (see p 29) in the dog consists only of the paired

elas-tic funiculus nuchae It bridges over the cervical vertebral column from the

caudal end of the spinous process of the axis and extends to the spinous

process of the first thoracic vertebra Here it is continued by the

supraspinous ligament with loss of elasticity and attaches to the spinous

process of all the vertebrae up to the third sacral vertebra

The ligamenta flava extend as short elastic ligaments from vertebral arch

to vertebral arch and thus close the interarcuate spaces dorsally

Interspinous ligaments are lacking The M interspinalis lies between the

spinous processes of adjacent vertebrae

c) L IGAMENTS OF THE A TLANTO -O CCIPITAL AND A TLANTO -A XIAL J OINTS ,

AND OF THE T HORAX

At the atlanto-occipital joint, the dorsal atlanto-occipital membrane

rein-forces the joint capsule and bridges over the atlanto-occipital space (access

to the cerebellomedullar cistern for withdrawal of cerebrospinal fluid for

diagnostic purposes) The ventral atlanto-occipital membrane is a ventral rein-forcement of the joint capsule The lateral ligament is a lateral rein-

forcement of the joint capsule

On the atlanto-axial joint the dens is held to the floor of the vertebral canal and to the occipital bone by the apical ligament of the dens, the transverse

atlantal ligament and the alar ligaments The transverse atlantal ligament

is underlain by a synovial bursa and is attached to either side of the atlas

In the case of rupture of these ligaments or fracture of the dens following car accidents or strangulation, damage to the spinal cord may occur with

paralysis and death as consequences The elastic dorsal atlanto-axial

mem-brane extends from the cranial projection of the spine of the axis to the

dor-sal arch of the atlas

The joints between the articular processes of the vertebrae lack ligaments

The joint capsule is either tightly attached or more loose according to the degree of movement and influences the direction of the movement, which depends on the position of the articular surfaces

At the joint of the rib-head, the intra-articular ligament of the head of the

rib connects the costal heads of both sides and lies over the intervertebral

disc It is also called the intercapital ligament It is lacking at the first and the last two pairs of ribs The radiate ligament of the head of the rib is pre-

sent as a strengthening of the joint capsule

At the costotransverse joints, the joint capsule is reinforced by a

costo-transverse ligament.

5 Articulations of the Vertebral Column and of the Thorax;

Atlanto-Occipital and Atlanto-Axial Joints

a) J OINTS (A RTICULATIONS )

Composition

I Atlanto-occipital joint Occipital condyles and Elliptical joint, Hinge joint, Right and left joint cavities

cranial articular foveae simple joint dorsal and ventral communicate ventrally

of the atlas flexion

II Atlanto-axial joint Fovea of the dens and Trochoid joint, Axial rotation The atlanto-axial joint communicates

caudal articular fossa of simple joint of the head on with the atlanto-occipital joint

the atlas, dens and ventral the neck, head articular surface of the dens ‘shaking’

III Joints of the Articular processes Plane joints Sliding joints Considerable mobility in the cervical articular processes of adjacent vertebrae region, decreasing in the thoracic and

costal fovea of the same-numbered (the more caudal) vertebra

V Joint of the rib tubercle Articular surface of the Plane joint, Hinge joint On the last ribs, the costotransverse

(costotransverse joint) costal tubercle and the simple joint joint approaches and then fuses with the

costal fovea of the trans- costovertebral joint

verse process of the same numbered (the more caudal) vertebra

VI Sternocostal joint Cartilaginous ends of Condylar joint, Hinge joint The first rib articulates with the

manu-the first to manu-the eighth simple joint brium of manu-the sternum The ninth (last ribs and the sternum sternal) rib is not connected to the sternum

by a synovial joint but by fibrous tissue

VII Costochondral Costal bone and Synchondrosis Nearly rigid and Postnatally a true joint may develop

synchondrosis costal cartilage immoveable from a synchondrosis

VIII Sternal synchondroses Manubrium of the sternum, Synchondrosis Increasingly Of the sternal synchondroses, the

sternebrae of the body of the rigid and manubriosternal and xiphosternal sternum, xiphoid process immoveable synchondroses are specially named

IX Intervertebral symphysis Bodies of adjacent vertebrae, Intervertebral Slight The discs in the intervertebral region

(joints between the starting with the axis disc without mobility of the sacrum ossify in the secondbodies of adjacent and including the a space year of life

vertebrae) caudal vertebrae

X Sacroiliac joint See joints of the pelvic limb

1

2

3

Trang 18

vC4

D

ACB

D

vC5

BAE

vT5

F

C DG

Alar ligg.

Lat ligament Articular capsule

Articular capsule

Transverse atlantal lig.

Apical lig of dens Occipital condyle

Caudal extremity

Atlanto-occipital and atlanto-axial joints

Costovertebral joints Cranial extremity Joint of head of rib

Costal fovea Joints of articular process Interspinalis m.

A Dorsal longitudinal lig.

B Cran articular process

Intervertebral disc:

C Nucleus pulposus

E Radiate lig of head of rib

F Intra-articular lig of head of rib

H Costotransverse lig.

I Radiate sternocostal lig.

(see pp 9, 89, 91)

Trang 19

The origin of the muscles or, respectively, their attachment to the skull and

the cervical and thoracic parts of the vertebral column, the ribs and

ster-num (collectively, the trunk) as well as to the thoracic limb is decisive for

their designation as trunk-limb muscles Because they insert on part of the

shoulder girdle, it is also justified to designate them synonymously as

mus-cles of the shoulder girdle Of these musmus-cles, the serratus ventralis provides

the main synsarcotic junction between the trunk and the limb, its area of

rotation being found in the middle of the serrate surface of the scapula

The trapezius muscle originates with both its parts (according to Donat et al.,

1967, three parts) at the dorsal midline above the spinous processes of the

cer-vical and thoracic vertebrae Its thoracic part (7) ends in a cranioventral

direc-tion on the dorsal third of the spine of the scapula The cervical part (6) inserts

after a caudoventral course on the dorsal two-thirds of the spine of the

scapu-la Despite the different directions of their fiber course, both parts act as

pro-tractors of the limb This is because the thoracic part inserts dorsal to and the

cervical part ventral to the area of rotation of the synsarcotic trunk-limb

junc-tion The cleidocervical muscle (15) according to the nomenclature proposal

of Donat et al., 1967, is considered as a third part (clavicular part) of the

trapezius muscle It courses between the clavicular intersection (16) and the

dorsal midline of the neck The dorsal branch of the accessory nerve (13),

which innervates this muscle, appears between the cleidocervical muscle and the cervical part of the trapezius muscle at the apex of a muscularly bounded triangle, and can be followed further where the transection of the trapezius muscle (see the dissection instructions) begins

The omotransversarius muscle (14) runs as its name suggests between the

acromion and shoulder (omos) and the transverse process (wing) of the

atlas Innervation: nC 4vm Deep to its dorsomedial surface is the

superfi-cial cervical lymph node, which should be preserved

The latissimus dorsi muscle (8) arises from the broad thoracolumbar fascia

(9) and ends chiefly on the teres major tuberosity by common tendon with

the teres major It has attachments to the brachial fascia as well as to the major and minor tubercular crests of the humerus, by which a broad axil-

lary arch is formed The thoracodorsal nerve and vessels (see p 19) enter

the medial aspect of the muscle

The rhomboideus muscle (10) is covered by the trapezius muscle and sists of the M rhomboideus capitis (nC vm), M rhomboideus cervicis (nC vm) and M rhomboideus thoracis (nT vm) They originate at the nuchal crest and at the dorsal midline and end on the scapular cartilage Function:

con-To fix, elevate, and retract the thoracic limb; when the neck is lowered, to elevate the neck

Chapter 2: Neck and Chest Region (Cervical and Thoracic Region)

1 Cutaneous Muscles and Cutaneous Nerves of the Neck and Thoracic Wall

To demonstrate the cutaneous muscles a longitudinal incision is made through the skin on the left side of the body The incision should extend from the base of the ear to the midlevel of the scapula up to the ventral end of the last rib In doing this, the cutaneous muscles must be preserved At the ends of the incision at the base of the ear and at the level of the last rib, a transverse section is made through the skin, which is then reflected to the dorsal and ventral midlines The external jugular and omobrachial veins, which are superficially located, are examined first in order to avoid unintended damage to the vessels and the smearing of the dissection site with the coagulated blood

and thus bring about movement of the skin, for example, to ward off

insects

The cutaneus trunci muscle (4) converges in its fiber course to the axillary

fossa and to the ventromedian linea alba and is penetrated by fine

cuta-neous nerves Its motor innervation is by the lateral thoracic nerve (5), the

branches of which can be seen through the ventral half of this thin muscle

The platysma (2) can be seen extending from its origin on the dorsal

mid-line to the border between head and neck where it is continued by the

cuta-neus faciei muscle

The nerve supply of the cervical platysma (3) originates from the

caudal auricular nerve of the seventh cranial nerve (facial nerve) It crosses deep to the muscle in a dorsal paramedian course The nerve can be iden-tified by spreading the coarse fiber bundles of the muscle

The superficial sphincter colli muscle (1) is ventral on the neck with

trans-verse fibers that are closely attached to the skin

To demonstrate the cervical cutaneous nerves, cut the dorsal linear origin of the platysma and reflect the muscle cranially to the cranial transverse section

of the skin To demonstrate the thoracic cutaneous nerves, cut the cutaneus trunci muscle along the caudal transverse section of the skin at the level of the last rib as well as at the caudal border of the triceps brachii muscle and reflect it ventrally toward the linea alba In the ventral thoracic and abdominal regions in all cases the aponeurosis of the external abdominal oblique muscle (34) should be preserved

(they also contain autonomic fibers); they are the parts of the spinal nerves

that are visible subcutaneously The spinal nerves (e.g., nC4) divide at their

exit from the intervertebral foramen into a dorsal branch (d) and a ventral

branch (v) that further divide into a medial branch (dm or, respectively, vm)

and a lateral branch (dl or, respectively, vl) Except for the dorsal cervical

region, the deeply located medial branches contain predominantly motor

fibers, the lateral branches mainly sensory fibers for the supply of the skin

Of the eight cervical nerves, only nC1 passes through the lateral vertebral

foramen of the atlas The second through the seventh cervical nerves leave the

vertebral canal cranial to the vertebra of the same number, and the eighth

cer-vical nerve caudal to the seventh cercer-vical vertebra The first cercer-vical nerve

does not reach the skin of the neck with its dorsomedial branch (nC 1dm)

The major occipital nerve (nC 2dm) runs deep to the superficial

cervicoau-ricularis muscle to the occipital region The following nC 3 dm to nC 6dm are

often double The last two, nC 7dm and nC 8dm are small and do not

usual-ly reach the skin but end in the thick muscular layer The inner vation of the

dorsal cutaneous cervical region by dm-branches is dif ferent from the

arrangement in other regions of the body in which the skin is supplied by

lat-eral branches, and the musculature by medial The difference is clear when

one compares sites of emergence of the cutaneous nerves in the dorsal

cervi-cal and dorsal thoracic regions

I The dorsal cutaneous branches of the cervical nerves reach the dorsal

midline in the company of cutaneous blood vessels and are formed by

dm-branches

II The dorsal cutaneous branches of the thoracic nerves appear a

hands-breadth dorsal and paramedian; that is, they are more lateral and are ularly formed by dl-branches They are accompanied by cutaneous blood vessels The thirteen thoracic nerves leave the vertebral canal caudal to the vertebra of the same number and divide into a dorsal and a ventral branch The ventral branch passes as an intercostal nerve ventrally between the ribs and gives off a vl (prox or lateral cutaneous)-branch about the middle of the length of the intercostal space and a vl (dist or ventral cutaneous)-branch at the ventral end of the intercostal space

reg-III The ventral cutaneous branches of the cervical nerves are in a

ventro-lateral row and are formed by vl-branches (nC 2vl to nC 5vl) The nC 2v through nC 5v communicate with each other and form a cervical plexus in the depth of the musculature The ventral cutaneous nerve of C2 runs with

its great auricular nerve (11) to the base of the ear and with its transverse

cervical nerve (12) to the ventral cervical region and the caudal part of the

mandibular space The ventral branches of C6 to T2 join to form the brachial plexus with their main parts (see p 19), and it is from this plexus that the plexus nerves of the thoracic limb originate

IV The lateral cutaneous branches of the thoracic nerves are formed by the

proximal vl-branches (lateral cutaneous branches of the intercostal nerves) mentioned above

V The ventral cutaneous branches of the thoracic nerves are formed by the

distal vl branches (ventral cutaneous branches of the intercostal nerves) These nerves are very small

2 Dorsal Extrinsic Limb Muscles

Knowledge of the bones of the shoulder girdle is required for the dissection (see p 17) In the course of the dissection, the cleidocervical and trapezius muscles are cut along the course of the dorsal branch of the accessory nerve (cranial nerve XI) and reflected to either side Following this, the division of the accessory nerve into a long dorsal and a short ventral branch can be demonstrated

Trang 20

T13dl

34

2928

14

g

C vl 5

C vl 415

1918

ab17

24

j25

26

1522

m Lateral thoracic a., v and n.

n Int thoracic a and v (cutaneous br.)

19 Clavicular part brachialis m.)

(cleido-20 Acromial part

21 Scapular part

22 Brachialis m.

23 Extensor carpi radialis m.

24 Lateral head of triceps m.

25 Long head of triceps m.

26 Teat (mammary papilla)

27 Sternohyoid and sternothyroid mm.

1 Superficial sphincter colli m.

2 Platysma

3 Platysma branch of facial nerve (VII)

Trang 21

a) Like the subclavian and internal jugular veins, the E XTERNAL J UGULAR VEIN

(8) originates from the brachiocephalic vein at the level of the thoracic inlet

In caudal-cranial sequence, it gives off the cephalic, superficial cervical and

omobrachial veins It then divides at the caudal border of the mandibular

gland into a dorsal branch, the maxillary vein (19), and a ventral branch, the

linguofacial vein (18) At its union with the external jugular vein, the

cephal-ic vein (11) lies in the medial part of the lateral pectoral groove and joins the

external jugular just cranial to the thoracic inlet The superficial cervical vein

(10) is satellite to the extrathoracic part of the same-named artery; it joins the

external jugular near the root of the neck, usually just opposite the cephalic

vein The omobrachial vein (9) courses superficially upon the deltoid and

clei-docervical muscles; it extends between the axillobrachial vein and the

exter-nal jugular The axillobrachial vein passes dorsally from the cephalic along the

lateral border of the cleidobrachialis muscle, then deep to the deltoid muscle

to join the caudal circumflex humeral vein (see p 21)

jugular vein (22) runs along the dorsolateral border of the trachea and gives

off branches for the brain, thyroid gland, larynx and pharynx The left and

right common carotid arteries originate at the level of the thoracic inlet from

the arterial brachiocephalic trunk (see p 49) The common carotid artery

(24) courses cranially on the dorsolateral border of the trachea and

dis-patches branches to the thyroid gland, larynx and pharynx The

vagosym-pathetic trunk (23) is a large nerve that lies dorsal to the common carotid

artery It conducts sympathetic fibers from the thoracolumbar sympathetic

trunk to the head (see p 49) Parasympathetic constituents of the vagus

nerve (tenth cranial nerve) reach from the head predominantly to the body

cavities After its separation from the sympathetic trunk, the vagus nerve

gives off the recurrent laryngeal nerve (see p 49) within the thoracic cavity

and after this contains parasympathetic and sensory nerve fibers, and

per-haps skeletal motor fibers for the esophagus The recurrent laryngeal nerve

(26) with its skeletal motor, autonomic and sensory fibers turns and passes

cranially in the neck It lies within the connective tissue laterlly on the trachea

that, like the esophagus, receives branches from it The recurrent laryngeal

nerve is easily found as it passes dorsal to the thyroid gland; its terminal part

are considered here The tracheal (jugular) lymphatic trunk is the large paired lymphatic trunk of the neck It begins as the efferent drainage of the medial retropharyngeal lymph node, receives afferent vessels from the super-ficial and deep cervical lymph nodes and empties at the venous angle formed

by the confluence of external and internal jugular veins At its termination,

the left tracheal lymphatic trunk (28) joins the thoracic duct (29), which ducts the lymph from the body cavities The medial retropharyngeal lymph

con-node (1) lies at the cranial attachment of the sternothyroid muscle It receives

its lymph from the head The superficial cervical lymph node (27) lies deep to

the omotransversarius muscle, between it and the serratus ventralis Its ent vessels pass from the superficial cervical area, and also from the trunk, head, and thoracic limb The deep cervical lymph nodes lie close to the tra-chea and consist of an inconstant cranial, middle and caudal group Their afferents are from their immediate surroundings in the neck

and parathyroid glands The cervical part of the esophagus (25) lies dorsal

to the trachea in the middle of the neck and dorsolateral (to the left) at the thoracic inlet Its reddish color is due to its external coat of striated mus-cle This striated muscle of the visceral type is innervated by the vagus

nerve The trachea (6) consists of C-shaped incomplete cartilaginous rings

that are closed off by a membranous part that contains transverse bundles

of trachealis (smooth) muscle The incomplete cartilaginous rings and their complementary membranous parts are connected to each other by anular ligaments The tracheal lumen is kept open by the incomplete cartilaginous rings that are braced by fibroelastic tissue The tension thus created makes possible the changes in tracheal length with respiration and swallowing and is responsible for the typical round cross-section of the trachea, which

can be narrowed by contraction of the trachealis muscle The thyroid gland

(21) lies at the cranial end of the trachea with left and right lobes that

some-times may be connected by a slight ventral isthmus The bilateral pairs of

parathyroid glands (20) lie on the thyroid gland as pale, rounded glands

with a diameter of about three millimeters They lie on the lateral and

3 Ventral Extrinsic Limb Muscles

In the course of the dissection, the superficial and deep pectoral muscles are transected a fingerbreadth lateral to the ventral midline In this way, their innervation by cranial and caudal pectoral nerves can be observed

The function of the trunk-limb muscles consists in the movement of the head,

vertebral column and thoracic limb, and in the suspension of the trunk by the

thoracic limbs The more ventral muscles act more in the suspension of the

trunk and therefore are rich in tendinous intersections; whereas, the more

dorsal muscles are more functional in limb movement and the suspension of

the thoracic limb is an accessory function

With the clavicular part of the deltoid muscle (cleidobrachialis), the

super-ficial pectoral muscles form the lateral pectoral groove In the dog, the

cephalic vein occupies only the most medial part of the groove as, at this

level, it does not pass in the main part of the groove, but medially upon the

superficial pectoral, deep to the cleidobrachialis The broad transverse

pec-toral muscle (14) takes linear origin from the manubrium and cranial part

of the body of the sternum The more superficial descending pectoral

mus-cle (15) arises only from the manubrium The two parts of the superficial

pectoral end on the crest of the major tubercle of the humerus

The principal portion of the deep pectoral muscle (17) forms the base for

the narrow, laterally located accessory portion (16) The deep pectoral

muscle has its origin from the manubrium and body of the sternum and

ter-minates at the major and minor tubercles The accessory portion inserts on

the brachial fascia The nerves that supply the deep pectoral can be seen on

its cut surface

The serratus ventralis muscle (31) is subdivided into the cervical serratus

ven-tralis muscle (nCvm) and the thoracic serratus venven-tralis muscle (long thoracic

nerve —30) The two fuse with each other in the area of the thoracic inlet

They originate from the transverse processes of the cervical vertebrae or,

respectively, the ribs and insert jointly on the facies serrata of the scapula

The sternocleidomastoid muscle (ventral branch of the accessory nerve)

consists of three individual muscles: The cleidomastoid (5) and

sternomas-toid (3) muscles fuse cranially; the sternomassternomas-toid muscle and

sterno-occip-ital muscle (4) fuse caudally The lateral surface of the sternocleidomastoid

muscle forms the jugular furrow for the external jugular vein The

inner-vation by the ventral branch of the accessory nerve is to the deep face of the

sternomastoid and sterno-occipital muscles caudal to the mandibular

gland Here, the ventral branch (see p 13) lies between the sternomastoid

and sterno-occipital muscles, which form a continuous muscle and can

only be separated artificially The accessory nerve divides into the ously identified dorsal ramus, which communicates with nC 2, and into the short ventral ramus whose three branches end after a short course in the

previ-individual muscles that together comprise the sternocleidomastoideus

The deltoid muscle has scapular, acromial, and clavicular parts; the clavicular

part is also designated the cleidobrachialis muscle (13) because it extends from

the clavicular intersection to the humerus, the bone of the brachium The

scapu-lar and acromial parts of the deltoid muscle are supplied by the axilscapu-lary nerve, a

branch of the brachial plexus The cleidobrachialis muscle is innervated by the

accessory axillary or brachiocephalic nerve (nC 6 – 12), the most cranial branch

of the brachial plexus It enters the deep surface of the cleidobrachialis two

fin-gerbreadths distal to the clavicular intersection The term brachiocephalicus

muscle is a collective term for a continuous muscle that, in domestic mammals,

is formed by parts of the deltoid and sternocleidomastoideus muscles, and by the cleidocervicalis Its three parts have an attachment to the clavicular intersection

and are the cleidobrachialis, cleidomastoideus, and cleidocervicalis The brachialis extends from the humerus to the clavicular intersection The clavicu-

cleido-lar intersection is a thin layer of connective tissue that crosses the

brachio-cephalicus muscle cranial to the shoulder; at its medial end, it contains a small cartilage and often a small bone that is visible radiographically The intersection attaches the fibers of the cleidobrachialis on its distal side; the fibers of the clei-docervicalis and cleidomastoideus on its proximal side, and is a complete parti-tion between the attaching muscle fibers The cleidomastoideus arises from the clavicular intersection and joins the sternomastoideus (see above) to insert on the mastoid process of the temporal bone The cleidocervicalis arises from the clavicular intersection superficial to the cleidomastoid From the intersection, the cleidocervicalis extends craniodorsally to the median fibrous seam of the

neck that attaches right and left muscles dorsally The term cleidocephalicus

muscle is applied to the cleidomastoid and cleidocervical muscles together and

the brachiocephalicus may therefore be described as consisting of the brachialis and cleidocephalicus

cleido-The sternohyoid muscle (nC 1vm – 7) and the sternothyroid muscle (nC 1vm

– 2) do not belong to the trunk-limb musculature, but to the long hyoid cles The right and left sternohyoid muscles contact each other at the ventral midline of the neck The sternothyroideus muscle is adjacent laterally

mus-4 Nerves, Vessels, and Visceral Organs of the Neck

The jugular furrow and external jugular vein have been dissected To demonstrate structures of the ventral neck, the sternohyoid muscles are separated

in the midline and transected jointly with the sternothyroideus muscles

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notch (49), forms the distal articulation with the articular circumference of

the ulna The distal radius ends medially with the medial styloid process

(50).

II The ulna projects beyond the head of the radius with its olecranon (51),

which is enlarged proximally to form the tuber olecrani (52) The

semilu-nar trochlear notch (54) begins at the pointed anconeal process (53) from

which it curves distally, medially and laterally, to reach the medial coronoid

process (55) or, respectively, lateral coronoid process (56) The radial notch (57) lies at the transition to the body of the ulna (58) The head of the ulna (59) forms the distal (!) end of the bone It possesses the articular circum- ference (60) medially and ends distally with the lateral styloid process (61)

The interosseous space of the antebrachium (62) is especially wide in the

distal third of the antebrachium

d) The C ARPAL B ONES are laid down in the embryo in three rows and are

reduced postnatally to two rows The medial radial carpal bone (63)

con-tains the intermediate carpal bone of the proximal row as well as the tral carpal bone of the middle row and is also called the intermedioradial

cen-carpal bone The ulnar cen-carpal bone (64), which is distal to the ulna, and the laterally projecting accessory carpal bone (65) complete the proximal row

Carpal bones I – IV (66) form the distal row and articulate with the

metacarpal bones

Synonyms for the carpal bones:

Radial carpal bone Os scaphoideum

Ulnar carpal bone Os triquetrumAccessory carpal bone Os pisiformis Carpal bone I Os trapeziumCarpal bone II Os trapezoideumCarpal bone III Os capitatum

e) The M ETACARPAL B ONES I–V have a basis (67) with an articular surface

proximally, a long body (68) and finally a distal (!) head (69) Metacarpal

I may be absent or divided into two bones in which case the proximal part

is fused with the first carpal bone

f) The B ONES OF THE D IGIT are the proximal, middle and distal phalanges

On digit I, the thumb (pollex), the middle phalanx is usu ally absent The

proximal phalanx (70) and the middle phalanx (71) have a basis (72)

prox-imally, a body (73) and a distal head (74) The indistinct flexor tuberosity

(75) is proximopalmar on the middle phalanx; it serves for the termination

of the superficial flexor tendon The distal phalanx or unguicular bone (76) has an articular surface (77) proximodorsally, an indistinct extensor

process (78) for the insertion of the extensor tendon and proximopalmarly

an indistinct flexor tubercle (79) for the attachment of the deep flexor don The sharp-edged unguicular crest (80) overlies the unguicular sulcus

ten-(81) and the basis of the unguicular process (82), which bears the claw g) The S ESAMOID B ONES of the manus are the sesamoid bone of the abduc-

tor digiti I muscle (83), which articulates with a small mediopalmar facet

of the radial carpal bone, and proximal sesamoid bones (84), which are

palmar at the metacarpophalangeal joints On the palmar side of the distal

interphalangeal joint there is a distal sesamoid (85) Dorsally on the imal interphalangeal joint there is a dorsal sesamoid (86) that is always car-

prox-tilaginous (sesamoid cartilage), and the sesamoid that is dorsal at the metacarpophalangeal joint is occasionally cartilaginous

Chapter 3: Thoracic Limb

1 The Skeleton of the Thoracic Limb

The pectoral (shoulder) girdle consists of scapula, coracoid bone and clavi

-cle, which are completely developed as individual bones in many

verte-brates below the mammals (e.g., birds) In the domestic mammals there is

a considerable reduction of the coracoid to a coracoid process of the

scapu-la and of the cscapu-lavicle to the cscapu-lavicuscapu-lar intersection, a connective tissue strip

within the brachiocephalicus muscle (see p 14) There often remains as

well a small bony remnant of the clavicle, which may be observed radio

-graphically at the medial end of the clavicular intersection It appears as a

lamina of bone and cartilage ca 10 x 5 mm

a) The S CAPULA is the main constituent of the shoulder girdle The costal

surface (1) of the scapula is subdivided into a dorsally situated facies

serrata (2), the area of insertion of the serratus ventralis muscle, and a

ven-trally located subscapular fossa (3), the area of attachment of the

sub-scapularis muscle The lateral surface (4) is subdivided by the spine of the

scapula (5) into a supraspinous fossa (6, –origin of the supraspinatus

mus-cle) and an infraspinous fossa (7, –origin of the infraspinatus musmus-cle) At

the ventral end of the spine of the scapula is the acromion (8) with a distal

hamate process (9) The caudal margin (10) of the scapula is nearly

straight; the cranial margin (11) has a scapular notch (12) distally , and the

dorsal margin (13) bears a narrow scapular cartilage (14) Of its three

angles (caudal (15), cranial (16) and ventral (17) angles), the ventral one

has a shallow oval glenoid cavity (18) Caudodistal to the slight neck of the

scapula (19) is the infraglenoid tubercle (20) and craniodistally from the

neck, the supraglenoid tubercle (21) with the craniomedial coracoid

process (22).

b) The H UMERUS bears the head of the humerus (23) as an articular

promi-nence for the shoulder joint The head is separated distinctly from the neck

of the humerus (24) only caudally The crest of the greater tubercle (26)

passes distally from the cranial margin of the greater tubercle (25), and the

line of the triceps muscle (27) passes proximocaudally from the deltoid

tuberosity; it passes caudal to the greater tubercle The intertubercular

groove (28) seats the tendon of origin of the biceps brachii muscle and

forms the deep furrow that defines the lesser tubercle (29) medially From

the lesser tubercle, the crest of the lesser tubercle (30) extends distally

where it passes over into the lateral supracondylar crest The body of the

humerus (31) bears the deltoid tuberosity (32) laterally at the junction of

its proximal and middle thirds The deltoid tuberosity serves for the

inser-tion of the deltoid muscle From the deltoid tuberosity, the humeral crest

(33) continues distally to the medial epicondyle The crest bounds

cranial-ly the spiralcranial-ly coursing groove of the brachialis muscle (34), which is

occu-pied by the brachialis muscle The humeral condyle (35) consists of a large

medial trochlea (36) for articulation with the ulna and the small lateral

capitulum humeri, which articulates with the radius The humeral condyle

bears an epicondyle on either side From the lateral epicondyle (38,

bear-ing roughnesses for the origin of the lateral collateral ligament and lateral

digital extensor, and a caudal facet for the origin of the ulnaris lateralis

muscle), the distinct lateral supracondylar crest (38') extends proximally

The medial epicondyle (39) is the process for attachment of the medial

col-lateral ligament and, caudally, the digital and carpal flexors The deep,

cau-dal olecranon fossa (40) and the shallow radial fossa (41) communicate by

the supratrochlear foramen (42), which is closed off in life by membrane

c) The B ONES OF THE A NTEBRACHIUM are the radius and ulna

I On the radius, the head of the radius (43) has a caudomedial condylar

articular circumference (44) for the proximal articulation with the ulna at

its radial notch The neck of the radius (45) is indistinct and bears

caudo-medially a small prominence, the radial tuberosity (46), for the termination

of the radial insertion of the biceps brachii muscle The body of the radius

(47) is continued distally by the trochlea of the radius (48), which

articu-lates distally with the carpal bones, and laterally, by means of the ulnar

1

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Bones of thoracic limb

Scapula

Costal surface (1) Facies serrata (2) Subscapular fossa (3) Lateral surface (4) Spine of scapula (5) Supraspinous fossa (6) Infraspinous fossa (7) Acromion (8)

Hamate process (9) Caudal margin (10) Cranial margin (11) Scapular notch (12) Dorsal margin (13) Scapular cartilage (14) Caudal angle (15) Cranial angle (16) Ventral angle (17) Glenoid cavity (18) Neck of scapula (19) Infraglenoid tubercle (20) Supraglenoid tubercle (21) Coracoid process (22)

Intertubercular groove (28) Lesser tubercle (29) Crest of lesser tubercle (30) Body of humerus (31) Deltoid tuberosity (32) Humeral crest (33) Sulcus for brachialis muscle (34) Humeral condyle (35)

Trochlea humeri (36) Capitulum humeri (37) Lateral epicondyle (38) Lateral supracondylar crest (38') Medial epicondyle (39)

Olecranon fossa (40) Radial fossa (41) Supratrochlear foramen (42)

Head of radius (43) Articular circumference (44) Neck of radius (45)

Radial tuberosity (46) Body of radius (47) Trochlea of radius (48) Ulnar notch (49) Medial styloid process (50)

Olecranon (51) Tuber olecrani (52) Anconeal process (53) Trochlear notch (54) Medial coronoid process (55) Lateral coronoid process (56) Radial notch (57)

Body of ulna (58) Head of ulna (59) Articular circumference (60) Lateral styloid process (61) Interosseous space of antebrachium (62)

Radial carpal bone (63) Ulnar carpal bone (64) Accessory carpal bone (65) Carpal bones I-IV (66)

Basis (67) Body (68) Head (69)

Proximal phalanx (70) Middle phalanx (71) Basis (72) Body (73) Head (74) Flexor tuberosity (75) Distal phalanx (76) Articular surface (77) Extensor process (78) Flexor tubercle (79) Unguicular crest (80) Unguicular sulcus (81) Unguicular process (82)

(palmar view)

(dorsolateral view)(lateral view)

(medial view)

Trang 25

a) The V EINS are identified on the basis of their area of drainage The

sequence of branches serves only as an auxiliary criterion because it varies

considerably in the venous system In the arterial and nervous systems, the

variations are less

The very short subclavian vein is continued at the level of the first rib by

the axillary vein (21), which releases first the (often doubly developed)

external thoracic vein (22) to the pectoral muscles A further venous

branch, the lateral thoracic vein (4), is given off and passes with the

same-named artery and nerve It runs along the lateral border of the deep

pec-toral muscle (see p 13) or, respectively, of the latissimus dorsi muscle At

its origin, it contacts the axillary lymph node (21) and, at the level of the

second intercostal space, the accessory axillary lymph node (3) From the

axillary vein then the subscapular vein (5) courses to the same-named

mus-cle and the thoracodorsal vein (2) to the medial aspect of the latissimus

dor-si muscle The subscapular vein releases the caudal circumflex humeral vein

(18), which passes deeply, coursing in an arciform manner laterally upon

the caudal aspect of the humeral joint capsule, and anastomosing laterally

with the cranial circumflex humeral vein (23) (see p 25) The latter is a

very slight vein that originates from the axillary vein and courses to the

hilus area of the biceps brachii muscle After branching off the

axillo-brachial vein (see p 25), which can also originate from the caudal

circum-flex humeral vein, the axillary vein is continued by the brachial vein (6) On

the flexor aspect of the elbow joint, the latter gives off the superficial

brachial vein (10), the continuation of which, the median cubital vein (27),

originates from the cephalic vein The brachial vein passes deep to the

pronator teres, gives off the common interosseous vein (12) and is

contin-ued by the median vein (13).

b) The S PINAL N ERVES nCv 6 to nTv 2 form the roots of the brachial plexus

in which the ventral branches of these several spinal nerves intermesh with

an exchange of fibers The major nerves of the thoracic limb originate as

branches of the brachial plexus In the following identification of nerves

and muscles, the nerves serve as guiding structures in determining the

homologies of the muscles and, on the other hand, the nerves are identified

on the basis of their area of supply

The axillary nerve (nC 7 and 8, —17) sends a branch to the teres major

muscle (1), the muscle arising proximally at the caudal margin of the

scapula and terminating, with the latissimus dorsi, on the humerus The

axillary nerve innervates additionally the caudal part of the subscapular

muscle as well as the shoulder joint At the caudal border of the

subscapu-lar muscle, the nerve passes deeply, runs laterally ventral to the long head

of triceps and appears finally on the lateral surface of the shoulder (see p

21) The accessory axillary nerve (brachiocephalic nerve, nC 6 and 7, —1 5 )

is the most cranial branch of the brachial plexus (its origin as a branch of

the brachial plexus is disputed by some authors) It extends to the

clavicu-lar part of the deltoid, pro viding the motor supply to that muscle, and

pen-etrates the muscle with its sensory cutaneous branch The subscapular

nerve (nC 6 and 7, —1 6) enters the subscapular muscle (16) with two

branches The subscapular muscle originates in the subscapular fossa and

ends on the lesser tubercle of the humerus The suprascapular nerve (nC 6

and 7, —14) passes laterally, deeply between the subscapular and

supraspinatus muscles It crosses the cranial aspect of the neck of the

scapula and appears on the lateral surface of the scapula deep to the

supraspinatus and infraspinatus muscles (see p 21) The

musculocuta-neous nerve (nC 6 – nT 1, —2 5) lies upon the cranial face of the brachial

artery Its proximal muscular branch supplies the coracobrachialis and

biceps brachii muscles and, a fingerbreadth proximal to the elbow joint,

the musculocutaneous nerve communicates with the median nerve It then

proceeds craniomedially deep to the biceps brachii and ends in a distal

muscular branch for the brachialis (there may be an additional branch to

the biceps brachii muscle) and the medial cutaneous antebrachial nerve

(11) The latter nerve passes craniodistally between the biceps and

brachialis muscles, arriving subcutaneously and descending the

craniome-dial forearm The short, fusiform coracobrachialis muscle (20) originates

on the coracoid process and terminates at the level of the proximal third of

the humerus caudal to the lesser tubercle The tendon of origin of the long

biceps brachii muscle (26) arises from the supraglenoid tubercle of the

scapula and, enveloped by a cranial extension of the synovial joint capsule,

verse humeral ligament Its tendon of insertion (see text-illustration) splits Y-like distal to the flexor aspect of the elbow joint and inserts on the prox-

imal radius (radial tuberosity) and ulna The brachialis muscle (see

text-illustration) runs with its insertion tendon between the branching tendons

of the biceps brachii, reaching the proximal medial margin of the ulna and the radius The brachialis originates caudal to the head of the humerus, winds spirally in the groove of the brachialis muscle from caudal to latero-cranially around the humerus, then distomedially, and ends on the proxi-

mal ulna The radial nerve (nC 7 – nT 2, —1 9) passes deeply distal to the

strong insertion tendon of the teres major muscle, entering between the medial and long heads of the triceps brachii muscle, which it innervates

Before it enters the triceps, it gives off a small branch to the tensor fasciae

antebrachii muscle (7) The latter muscle originates from the insertion

ten-don of the latissimus dorsi muscle and terminates on the olecranon and the

medial antebrachial fascia The ulnar nerve (nC 8 – nT 2, —8) and median

nerve (nC 8 – nT 2, —2 4) originate jointly from the brachial plexus and

separate from each other in the distal arm region, the ulnar inclining dally Throughout their course in the proximal arm, the two nerves lie together caudal to the brachial artery and in association with the brachial vein The smaller median nerve is the more cranial At the distal third of

cau-the humerus, cau-the ulnar nerve dispatches cau-the caudal cutaneous antebrachial

nerve (9), which passes on the extensor aspect of the elbow joint and

dis-tally on the caudal forearm The cranial and caudal pectoral nerves, the

long thoracic nerve, the thoracodorsal nerve and the lateral thoracic nerve

are also accounted as nerves of the brachial plexus

2 Medial Veins of the Thoracic Limb; Medial Shoulder and Arm Muscles

and their Nerve Supply

For its further dissection, the thoracic limb is separated from the trunk To do this, the cleidocephalicus muscle (see p 14) is cut proximal to the clavicular intersection, and the other trunk-limb muscles are severed a few fingerbreadths proximal to their insertion on the thoracic limb The external jugular vein is transected cranially from the origin of the omobrachial vein, and the subclavian vein from the brachiocephalic vein shortly after the latter’s division into sub-clavian and external jugular The axillary artery is cut just lateral to the first rib The segmental nerve roots (nCv 6 to nTv 2) are sectioned a short distance before their confluence to form the brachial plexus, in which case the three roots of the phrenic nerve (nCv 5 through 7) should be cut near their origin from plexus nerves nCv 6 – 7, and preserved in their course to the thoracic inlet With the thoracic limb removed, the skin of the limb is reflected to the level of the metacarpophalangeal joints In doing this, observe the carpal pad at the carpus, the metacarpal pad at metacarpophalangeal joint level and the digital pads

at the level of the distal interphalangeal joints The distal end of the limb must be kept wrapped and moistened to avoid its drying out In reflecting the skin, especially on the flexor aspect of the elbow joint and on the cranial contour of the antebrachium, preserve for later dissection the superficial veins and the cutaneous nerves that accompany them Medially at the elbow joint, the pronator teres muscle (42) is cut in order to demonstrate the veins

26 Biceps brachii m (origin)

20 Coracobrachialis m.

Brachialis m.

26 Biceps brachii m (insertion)

Pronator quadratus m.

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9 Caud cutaneous antebrachial n.

10 Superficial brachial vein

11 Medial cutaneous antebrachial n.

12 Common interosseous vein

13 Median vein and artery

14 Suprascapular a., v and n.

15 Accessory axillary n.

16 Subscapular n and m.

18 Caudal circumflex humeral vein

Transverse cubital a and v.

f Recurrent ulnar a and v.

g Ulnar a and v.

h Dors brr of ulnar a v and n.

i Caud interosseous a and v.

j Deep brachial a and v.

k Cephalic v.

l Medial br of supf cran antebrachial a.

and supf br of radial n (medial br.)

m Acc cephalic v.

n Radial a and v.

o Dors carpal br.

p Abaxial palmar digital n I

q Palm com digital aa and nn.

r Supf palmar arch

s Palm com digital vv.

Collateral ulnar a and v.

e

28 Serratus ventr thoracis m.

29 Serratus ventr cervicis m.

30 Latissimus dorsi m

31 Supraspinatus m.

32 Deep pectoral m (Section)

33 Pectoralis desc m (Section)

34 Pectoralis transv m (Section)

35 Clavicular part of m deltoideus Triceps brachii muscle:

50 Extensor carpi radialis m.

51 Palmar carpal ligament

52 Flexor retinaculum (Section)

53 Palmar anular ligament

Trang 27

a) The L ATERAL S UPERFICIAL C UTANEOUS V EINS course in the scapular and

arm region unaccompanied by same-named arteries From the external

jugular, the cephalic vein (19) passes briefly laterally in the lateral pectoral

groove, then deeply between the cleidobrachialis and superficial pectoral

muscles to reach the lateral border of the cleidobrachialis Here it joins the

axillobrachial vein (7) Before the axillobrachial vein passes deep to the

scapular part of the deltoid muscle, it receives the omobrachial vein (6) At

the flexor aspect of the elbow joint, the cephalic vein gives off the median

cubital vein (20), the continuation of which, as the superficial brachial

vein, reaches the medially situated brachial vein The cephalic vein in its

course upon the cranial contour of the antebrachium is accompanied by

both branches of the superficial ramus of the radial nerve and by the distal

continuation (cranial superficial antebrachial artery) of the weak

superfi-cial antebrachial artery Three fingerbreadths proximal to the carpus, the

cephalic vein passes onto the medial side of the limb, then caudopalmarly

to reach the palmar surface of the manus Distal to this point, its straight

direct-distal course upon the cranial aspect of the limb is continued by the

accessory cephalic vein (21), which dispatches the dorsal common digital

veins on the dorsum of the manus

b) The N ERVES that supply the L ATERAL M USCLES of the shoulder and

brachium originate medially at the shoulder from the brachial plexus,

where their initial portions were previously identified (see p 19)

The axillary nerve gives off muscular branches to the medial aspect of the

scapular and acromial parts of the deltoid muscle and to the fusiform teres

minor muscle After this, the axillary nerve terminates with its cranial lateral

cutaneous brachial nerve (10) and its cranial cutaneous antebrachial nerve

(11) These nerves appear subcutaneously at the caudal border of the deltoid

muscle in the company of the axillobrachial vein The deltoid muscle

origi-nates from the scapular spine with its scapular part (3) and from the acromion

with its acromial part (4) Both parts end on a common tendon that inserts on

the deltoid tuberosity of the humerus The clavicular part of the deltoid (5,

cleidobrachial muscle), runs between the clavicular intersection and the

dis-tal end of the humeral crest It is supplied by the accessory axillary nerve

(bra-chiocephalic nerve, –nC 6) The teres minor muscle (see text-illustration) originates at the infraglenoid tubercle and the caudal margin of the scapula

and terminates at the teres minor tuberosity The suprascapular nerve (2),

previously identified, innervates the supra spi na tus muscle It crosses the neck

of the scapula cranially, and turns caudally on the lateral surface of the

scapu-la at the base of the acromion, finally entering the deep face of the

infra-spinatus muscle The suprainfra-spinatus muscle (1) originates in the supraspinous fossa and inserts cranially on the greater tubercle of the humerus The infra-

spinatus muscle (9) lies deep to the scapular part of the deltoid muscle Its

ori-gin is the infraspinatus fossa and spine and cartilage of the scapula It ends on the infraspinatus facet of the humerus, a little distal to the greater tubercle Where its tendon crosses over the cartilage-covered caudal part of the greater tubercle, it is underlain by a subtendinous bursa The insertion tendons of the infraspinatus and subscapularis have the function of lateral or, respectively, medial contractile ligaments at the shoulder joint, which lacks proper collat-eral ligaments Deep within the fibrous joint capsule there are lateral and medial fibrous reinforcements that are designated glenohumeral ligaments

(see p 26) The radial nerve (15), passing deep to the lateral head of the

tri-ceps, supplies with its proximal muscular branches the heads of the triceps brachii muscle and the anconeus muscle The continuing radial nerve passes

distally upon the brachialis muscle and divides into a deep branch (17) for the digital and carpal joint extensors (and the ulnaris lateralis) and a superficial

branch (16) that accompanies the cephalic vein on either side with lateral and

medial branches These branches continue on the distal limb alongside the accessory cephalic vein Their dorsal common digital nerves supply the dor-sum of the manus The triceps brachii muscle (see also the small illustration)

originates with its long head (12) on the caudal margin of the scapula, with its accessory head (14) caudally on the humerus, with its lateral head (13) from the line of triceps and, with its medial head (8), proximomedially from

the humerus Deep to their common termination at the olecranon, a tendinous bursa is present laterally Proximal to the olecranon there is an

sub-inconstant subcutaneous olecranon bursa The anconeus (18) originates at

the margins of the olecranon fossa and ends with a fleshy attachment

lateral-ly on the olecranon

3

4

3 Lateral Veins of the Thoracic Limb; Lateral Shoulder and Arm Muscles

and their Nerve Supply

To demonstate the anastomoses between the medial deep and the lateral superficial venous systems as well as the muscular branches of the axillary nerve, the scapular and acromial parts of the deltoid muscle are severed at their origin from the scapula (see text-illustration) To demonstrate the mus-cular branches of the radial nerve, the lateral head of the triceps brachii muscle is cut in its middle and the stumps reflected

9 Infraspinatus m.

1 Supraspinatus m.

Trang 28

29 30

h i

g

34 19

j

35k36

lm

24a

20 Median cubital vein

11 Cranial cutaneous antebrachial nerve Triceps brachii muscle:

17 Deep br and collateral radial a and v.

10 Cranial lateral cutaneous brachial nerve

(craniolateral view)

21 Accessory cephalic vein

8 Medial head of triceps brachii m.

a Cutaneous brr of thoracodorsal a and v.

b Accessory axillary n (C )

c Supf brachial a and v.

d Cran supf antebrachial a

e Medial branch

f Lateral branch

g Lat cutaneous antebrachial n of radial n.

h Medial br of radial n (supf br.)

i Lateral br of radial n (supf br.)

j Dors com digital I a., v and n.

k Dors br of ulnar a and n.

l Abaxial dors dig a., v and n.

6

22 Cervical part of trapezius m (section)

23 Thoracic part of trapezius m (section)

30 Extensor carpi radialis m.

31 Extensor dig com m.

32 Extensor dig lat m.

33 Extensor carpi ulnaris m.

34 Abductor pollicis longus m.

35 Extensor pollicis m

Trang 29

a) The C AUDOMEDIAL F OREARM M USCLES are the two digital flexors, the two

flexors of the carpal joint and the two pronators of the radioulnar joints

The origin of all of these muscles except one (pronator quadratus) is from the

medial epicondyle of the humerus; additional to its origin from the medial

epi-condyle, the deep digital flexor has radial and ulnar heads The pronator

quad-ratus muscle is composed of horizontal fibers that occupy the antebrachial

interosseous space Two of the muscles have, in addition to their origin from the

medial epicondyle, an origin from the ulna (flexor carpi ulnaris muscle) and an

origin from the ulna and radius (deep digital flexor muscle) Thus, the flexor

carpi ulnaris has two heads of origin, the deep digital flexor, three

The insertion of the two digital flexors is on the digital bones; of the two

carpal joint flexors, at the carpus or proximal metacarpus; of the two

pronators on the radius and ulna (these are things to consider in

identify-ing the different muscles)

I Of the two digital flexor muscles, the superficial digital flexor (10) is

con-tinued at the distal third of the antebrachium by its tendon, which divides in

the proximal metacarpus into four branches, each inserting on a digit (II – V)

Proximal to their termination on the flexor tuberosity of the middle phalanx

the tendon is modified to form a tunnel or sleeve-like manica flexoria (20) for

the corresponding tendon-branch of the deep digital flexor The deep digital

flexor muscle has a strong humeral head (8) and weak ulnar (7) and radial (6)

heads that join in the distal third of the antebrachium to form the deep flexor

tendon The deep flexor tendon then divides at the distal carpus and proximal

metacarpus into five tendons of insertion (I – V), four of which pass through

the sleeve of the corresponding manica flexoria and end on the flexor tubercle

of the distal phalanx of digits II – V The branch of the deep flexor to the distal

phalanx of digit I is unaccompanied by a tendon of the superficial flexor

II Of the two carpal joint flexors, the two heads of the flexor carpi ulnaris

muscle (15) remain separate up to their insertion on the accessory carpal

bone The ulnar head is mainly tendinous, the humeral head

predominant-ly fleshy The flexor carpi radialis muscle (2) has a divided terminal tendon

and inserts on the proximopalmar aspect of metacarpal bones II and III

III Of the two pronator muscles of the radioulnar joints, the pronator teres

muscle (see text-illustration) inserts craniomedially on the proximal radius

The pronator quadratus muscle (4) occupies the antebrachial interosseous

space palmarly, and extends between the radius and ulna

The nerve supply is by the median (5) and ulnar nerves (9), in which case

the more medially located muscles (pronator teres, pronator quadratus and

flexor carpi radialis muscles as well as the radial head of the deep digital

flexor muscle) are supplied alone by the median nerve The median nerve

also supplies the superficial digital flexor, the most caudal of the medial

muscles The more caudally located muscles (flexor carpi ulnaris muscle

and ulnar head of the deep digital flexor muscle) are supplied only by the

ulnar nerve The humeral head of the deep digital flexor muscle, consisting

of three bellies and found in the middle of both areas of supply is

inner-vated by both the ulnar and median nerves The ulnar nerve divides in the

proximal antebrachial third into the palmar branch and the dorsal branch

The dorsal branch of the ulnar nerve (14) runs distally along the

caudolat-eral border of the ulnaris latcaudolat-eralis muscle (extensor carpi ulnaris muscle),

crosses the accessory carpal bone laterally, and ends as abaxial dorsal

dig-ital nerve V on the dorsum of the manus The palmar branch of the ulnar

nerve (17) courses deeply, within the carpal canal medial to the accessory

carpal bone and between the accessorometacarpal ligaments (ligaments

that extend from the accessory carpal bone to metacarpal bones IV and V;

see illustration on p 27), to reach the lateral palmar surface of the manus

b) The C RANIOLATERAL F OREARM M USCLES are the digital extensors, two

muscles of the pollex (digit I, homologous to the thumb of human beings),

two carpal extensors and two supinators of the radioulnar joints (see

text-illustration)

The origin of the craniolateral forearm muscles is predominantly from the

lat-eral supracondylar crest (brachioradialis, extensor carpi radialis, common

digital extensor), the lateral epicondyle of the humerus and the lateral

collat-eral ligament of the elbow joint (supinator, latcollat-eral digital extensor, extensor

carpi ulnaris or ulnaris lateralis) The long abductor of digit I (m abductor

pollicis longus) and the extensor of digit I (m extensor pollicis) arise from the

cranial surface of the ulna and radius and the interosseous ligament that joins

the two bones

The insertion of these muscles is brought into play in distinguishing the

dif-ferent muscles of the craniolateral group Of the four muscle groups, each

consisting of two individual muscles, the digital extensors insert distally on

the extensor process of the distal phalanx, the pollex muscles between the metacarpus and the distal phalanx of digit I, the carpal extensors directly distally to the carpus and the metacarpus, and the supinators on the radius

I Of the two digital extensors, the common digital extensor muscle (13)

ends on digits II – V and the lateral digital extensor muscle (16) on digits

III – V

II Of the two pollex (digit I) muscles, the long abductor of digit I (11)

inserts proximally on the first metacarpal bone, and the extensor of digit I

(12) ends with two very weak tendons on the first and second digits III Of the two extensors of the carpal joint (both are named ‘extensors’;

only the extensor carpi radialis functions as an extensor of the joint), the

extensor carpi radialis muscle (3) ends by dividing into two tendons that

insert proximally on metacarpal bones II and III The extensor carpi ulnaris

(ulnaris lateralis, —18), which acts chiefly as an abductor of the paw and

partial flexor of the carpus ends on the proximal lateral prominence of metacarpal V and with a transverse branch that attaches to the accessory carpal bone

IV Of the two supinators (see text-illustration), the supinator muscle lies

deep to the origins of the digital extensors and terminates

proximocranial-ly on the radius The brachioradialis muscle passes superficialproximocranial-ly on the

flex-or aspect of the elbow joint and inserts on the craniomedial margin of the radius at the junction of its middle and distal thirds

The nerve supply of these muscles is by the radial nerve, which, by its deep

branch (1), supplies all of the craniolateral forearm muscles The superficial

branch (see p 21) lies on both sides of the cephalic vein with its medial and lateral branches, and gives off the lateral cutaneous antebrachial nerve as the several branches that extend caudally from the lateral branch onto the cran-iolateral antebrachium In the company of the accessory cephalic vein, both the medial and lateral branches continue distally onto the dorsum of the

manus and branch here into the dorsal common digital nerves (19), each of

which ends by dividing proximal to the metacarpophalangeal joints into sal proper digital nerves that extend toward the ends of neighboring digits

dor-1

2

4 Antebrachial (Forearm) Muscles and their Nerve Supply

To clearly differentiate between the individual carpal and digital flexor muscles, the termination of their tendinous insertions has to be identified To do this, the carpal canal, passage for the two digital flexor tendons and associated structures on the palmar carpus, must be opened First, the superficial lamina

of the flexor retinaculum extending between the accessory carpal bone and the medial styloid process is cut The superficial flexor tendon is lifted up from the carpal canal Then the deep lamina of the flexor retinaculum, which lies between the flexor tendons, is cut After lifing up the deep flexor tendon, the palmar carpal ligament, which forms the deep boundary of the canal, can be seen To see the insertions of the extensor and flexor tendons, the skin of the second digit will be completely reflected The manica flexoria of the superficial flexor tendon is incised laterally and the passage of the deep flexor tendon through the manica can then be more easily observed

11 Abductor pollicis longus m.

16 Lateral digital extensor m.

13 Common digital extensor m.

18 Extensor carpi ulnaris m Supinator m.

Lat epicondyle of humerus

Trang 30

21 23

22

292520

24

30

31 2726

1 Deep branch of radial n.

2 Flexor carpi radialis m (section)

3 Extensor carpi radialis m.

10 Superficial digital flexor m

11 Abductor pollicis longus m

12 Extensor of digit I m.

13 Common digital extensor m.

14 Dorsal branch of ulnar nerve

15 Flexor carpi ulnaris m.

16 Lateral digital extensor m.

17 Palmar branch of ulnar nerve

18 Extensor carpi ulnaris m.

19 Dorsal common digital aa., vv and nn I-IV

20 Manica flexoria

21 Tendon of supf digital flexor

22 Tendon of deep digital flexor

23 Interosseus m.

24 Tendon of com dig ext m.

25 Palmar anular ligament

26 Prox and dist digital anular ligg.

27 Collateral lig of prox interphalangeal joint

28 Dorsal ligament

29 Prox sesamoid bone

30 Dorsal sesamoid bone

31 Dorsal sesamoid cartilage

32 Distal palmar sesamoid cartilage

Trang 31

a) S HOULDER , B RACHIUM (A RM ) AND A NTEBRACHIUM ( FOREARM ) are supplied

by blood vessels and nerves that run mainly medially and cranially on the

limb At the joints they are generally found on the protected, flexor, aspect

of the joint The blood supply of the thoracic limb is by a single artery, the

axillary artery The venous drainage is by several veins: the medially

situ-ated axillary vein, the craniolaterally locsitu-ated cephalic and the

axillo-brachial and omoaxillo-brachial veins

The axillary artery and vein (15) lie at the bend of the shoulder joint,

super-ficial to the axillary nerve At the level of the first rib, they continue the

long subclavian artery or, respectively, the very short subclavian vein and

give off the external thoracic and lateral thoracic vessels before ending by

dividing into the subscapular artery and vein and the brachial artery and

vein The cranial circumflex humeral vessels usually arise at the terminal

division of the axillary vessels or from the brachial artery and vein With

the cranial pectoral nerve, the external thoracic artery and vein (16) enter

the superficial pectoral muscle The lateral thoracic artery and vein (3) pass

with the same-named nerve on the lateral border of the deep pectoral

mus-cle; they supply the axillary lymph node and the inconstant accessory

axil-lary lymph node and the thoracic mammae Branches of the lateral thoracic

vessels, joined by caudal pectoral nerves, pass to the deep face of the deep

pectoral muscle The subscapular artery and vein (1) course at the caudal

border of the subscapular muscle The subscapular artery gives off

caudal-ly the thoracodorsal artery (2); whereas, the thoracodorsal vein (2)

usual-ly arises from the axillary vein With the same-named nerve, both vessels

enter the medial aspect of the latissimus dorsi muscle Additional branches

of the subscapular artery and vein are the caudal circumflex humeral artery

and vein (4), which run deeply, passing laterally caudal to the shoulder

joint, ventral to the long head of triceps, and anastomose with the weak

cranial circumflex humeral vessels The cranial circumflex humeral artery

and vein (17) pass cranially from the axillary or brachial vessels and enter

the biceps brachii muscle at its hilus The brachial artery and vein (5),

which proceed as end-branches of the axillary vessels, give off the deep

brachial, bicipital, collateral ulnar, superficial brachial and transverse

cubital arteries and veins After passing deep to the pronator teres muscle,

the brachial vessels end at the level of the proximal interosseous space by

dividing into common interosseous and median vessels About the middle

of the brachium, accompanied by the radial nerve, the deep brachial artery

and vein (6) pass deeply between the medial and long heads of the triceps,

which they supply In the distal brachium, the bicipital artery and vein (18)

pass cranially to supply the biceps brachii muscle The collateral ulnar

artery and vein (7) accompany the ulnar nerve to the extensor aspect of the

elbow joint and anastomose distally with the recurrent ulnar vessels that

proceed from the ulnar artery and vein The superficial brachial artery (8)

originates in the distal third of the brachium; the same-named vein closer

to the level of the elbow joint The artery and vein pass first superficially

and transversely across the flexor aspect of the elbow joint The superficial

brachial artery passes over distally into the superficial antebrachial artery,

whose branches initially join the cephalic vein and, continuing, pass onto

the dorsum of the manus, with the accessory cephalic vein On the flexor

aspect of the elbow joint, the very short superficial brachial vein (8) is

con-tinued by the median cubital vein The arrangement of the veins here is like

the letter ‘H’ The superficial brachial and median cubital veins form the

bar of the H The longitudinal branches of the ‘H’ are formed medially by

the brachial vein, laterally by the cephalic vein The transverse cubital

artery and vein (9) pass deep to the terminal part of the biceps brachii

mus-cle at the level of the flexor aspect of the elbow joint The common

interosseous artery and vein (10) give off the ulnar artery and vein (11),

which pass distally with the ulnar nerve The common interosseous vessels

end by dividing into cranial and caudal interosseous vessels The caudal

interosseous vessels run distally deep to the pronator quadratus muscle

The cranial interosseous vessels emerge cranially from the proximal

interosseous space and supply the craniolateral forearm muscles The

medi-an artery medi-and vein (12) arise as end-brmedi-anches of the brachial vessels In the

proximal third of the antebrachium, they give off caudally the deep

ante-brachial vessels (13) for the caudomedial forearm muscles and, a

finger-breadth distal, the small radial artery and vein (14) that pass along the

medial margin of the radius After this, the median artery (the satellite veins become very small) passes in the carpal canal and reaches the palmar sur-face of the deep digital flexor tendon

b) The V ESSEL AND N ERVE S UPPLY OF THE M ANUS is by deep and superficiaI arteries, veins and nerves On the dorsal and palmar surfaces of the manus,

the deeply located vessels and nerves are designated metacarpal arteries,

veins, and nerves; dorsal or palmar according to the surface of the manus

supplied The superficially located vessels and nerves are designated

com-mon digital arteries, veins, and nerves; again, dorsal or palmar according

to the surface of the manus The common digital vessels and nerves divide distally into proper digital vessels and nerves

I On the dorsum of the manus, the dorsal common digital arteries I – IV

proceed from the two branches of the superficial antebrachial artery sal common digital veins I – IV are from the accessory cephalic vein Dor-sal common digital nerves I – IV are from the medial and lateral branches (rami) of the superficial ramus of the radial nerve The dorsal branch of the ulnar nerve ends on the dorsum of the manus as the dorsal abaxial digital nerve of digit V The deeply located dorsal metacarpal arteries and veins I

Dor-– IV originate from the respective arterial and venous rete carpi dorsale

The venous carpal rete (carpal network) is formed by dorsal carpal

branch-es of the accbranch-essory cephalic and radial veins The arterial carpal rete is formed by dorsal carpal branches of the caudal interosseous, ulnar and radial arteries

II On the palmar surface of the manus, the palmar common digital

arter-ies and veins I – IV arise from the respective arterial and venous superficial palmar arches The arterial superficial palmar arch is formed in the proxi-mal metacarpus The medial arm of the arch is from the median and radi-

al arteries; its lateral arm proceeds from the union of the ulnar artery and palmar carpal branch of the caudal interosseous artery The venous super-ficial palmar arch lies farther distally, at the proximal margin of the metacarpal pad It is formed by a confluence of the cephalic and radial veins medially, by the ulnar and caudal interosseous veins laterally The palmar metacarpal arteries and veins I – IV originate in the proximal metacarpus from the respective arterial and venous deep palmar arches The arterial arch is formed medially by the radial artery and laterally by a confluence of the ulnar and caudal interosseous arteries The venous arch

is formed by the cephalic and radial veins medially and laterally by a fluence of the ulnar and caudal interosseous veins The palmar common digital nerves I – III arise from the median nerve, palmar common digital nerve IV from the superficial branch of the palmar branch of the ulnar nerve Palmar metacarpal nerves I – IV originate from the deep branch of the palmar branch of the ulnar nerve

con-c) The L YMPH D RAINAGEof the thoracic limb (see pp 15 and 19) is by ficially and deeply located lymph vessels The superficial lymph vessels pre-dominantly accompany the superficial lateral cutaneous veins and pass to

super-the superficial cervical lymph nodes from which super-the lymph drains to super-the

venous angle at the junction of internal and external jugular veins The deep lymph vessels accompany the deep blood vessels and pass to the axil-lary and accessory axillary lymph nodes, which also drain the lymph from

the thoracic wall and the three cranial mammae The disc-shaped axillary

lymph node, about 2 cm in diameter, can be palpated in the caudal angle

between the lateral thoracic and axillary vessels The accessory axillary

lymph node is located one intercostal space farther caudal on the course of

the lateral thoracic artery and vein The lymph passes from the axillary and accessory axillary lymph nodes to the venous angle also

5 Vessels and Nerves of the Thoracic Limb

Legend (see figure on opposite page)

19 Circumflex scapular a and v

28 Palmar abaxial a and n of digit V

29 Superficial palmar arch

30 Dorsal common digital aa., vv and nn (dorsal view)

Palmar common digital aa., vv and nn (palmar view)

31 Dorsal proper digital aa., vv and nn (dorsal view)

Palmar proper digital aa., vv and nn (palmar view)

32 Phrenic nerve

33 Axillobrachial v

34 Median n

35 Recurrent ulnar a and v

36 Cranial interosseous a and v

37 Caudal interosseous a and v

38 Interosseous branch

39 Dorsal branch of the ulnar a and n

40 Deep palmar arch

41 Musculocutaneous n

42 Medial cutaneous antebrachial n

43 Radial n

44 Superficial ramus

45 Lateral branch (ramus)

46 Medial branch (ramus)

47 Deep branch

48 Cranial superficial antebrachial a

49 Lateral branch (ramus)

50 Medial branch (ramus)

60 Palmar metacarpal aa., vv and nn I – IV

61 Dorsal abaxial n of digit I (dorsal view)Palmar abaxial n of digit I (palmar view)

62 Dorsal carpal branch of the radial a and v

63 Dorsal carpal branch of the caudal seous a

interos-64 Dorsal carpal branch of the accessory cephalic v

65 Dorsal carpal branch of the ulnar a

66 Rete carpi dorsale

67 Dorsal metacarpal aa and vv I – IV

68 Abaxial dorsal digital a., v and n of digit V

Trang 32

5243

444546

47

57

48

49 50

42

35

36

37 3839

58 5625

40

6226

27

606128

2930

31

61

306867

66656462

58

633938

36494556

5046

31

Arteries, Veins, Nerves of thoracic limb

(Basset Artésien - Normand)

10 Common interosseous a and v.

9 Transverse cubital a and v.

8 Superficial brachial a and v.

7 Collateral ulnar a and v.

6 Deep brachial a and v.

5 Brachial a and v.

4 Caudal circumflex humeral a and v.

3 Lateral thoracic a., v and n.

2 Thoracodorsal a., v and n.

1 Subscapular a., v and n.

18 Bicipital a and v.

17 Cranial circumflex humeral a and v.

16 External thoracic

a and v.

15 Axillary a and v.

Trang 33

6 Synovial Structures of the Thoracic Limb

a) J OINTS OF THE T HORACIC L IMB

Composition

I Shoulder (humeral) joint Glenoid cavity of the scapula, Spheroid joint/ Movement in all A capsular synovial sheath invests the

head of the humerus Simple joint directions, chiefly tendon of origin of the biceps brachii

a hinge joint muscle, which is kept in position by the (ginglymus) transverse retinaculum that bridges the

intertubercular groove

II Elbow (cubital) joint

trochlear notch Ginglymus joint digital extensor muscle; 2 Craniomedial

of the ulna recess deep to the biceps brachii muscle;

3 Caudal recess between the lateral

of the radius

III Distal radioulnar joint Ulnar notch of the radius, Trochoid joint/ Rotation of the The joint cavity communicates with the

be cut

Joints of the Manus

IV Carpal joint

radial carpal bone, compound joint hinge joint with communicate with each other Proximal

adduction the radioulnar joint Distal part: b) and c)

rein-forcement, the extensor retinaculum,

retinaculum bridges the carpal canal The

only the antebrachiocarpal joint

d) Intercarpal joints Joints between the carpal Plane joint/

bones of a row Compound joint (perpendicular joints)

e) Joints of the accessory Accessory carpal bone, Plane joint/ Amphiarthrosis

e) carpal bone ulnar carpal bone, ulna Compound joint (little movement)

V Metacarpophalangeal Proximal phalanges; Compound joint Mainly a hinge Metacarpophalangeal and interphalangeal joints proximal sesamoid bones; joint with slight joints have each in their joint capsules a

dorsal sesamoid bones; abduction and dorsal and a palmar outpouching The metacarpal bones adduction as well joint capsule attaches at the margin of the

as axial rotation articular surfaces of the participating

sesamoids At the metacarpophalangeal joint there are proximal sesamoids palmarly and a single dorsal sesamoid

VI Proximal interphalangeal Proximal and middle Saddle joint/ Dorsal sesamoid is present.

joints of the manus phalanges Simple joint VII Distal interphalangeal Middle phalanges and Saddle joint/ Distal sesamoid is present.

joints of the manus distal phalanges Simple joint

The shoulder joint lacks typical ligaments external to the joint capsule

Their function is taken over by contractile tension-bands, the tendons of

the infraspinatus and subscapular muscles The lateral and medial

gleno-humeral ligaments are ‘internal’ capsular reinforcements

At the elbow joint the collateral ligaments bifurcate, forming radial and

ulnar attachments The anular ligament of the radius grips around the head

of the radius and extends from the medial coronoid process of the ulna to

the lateral collateral ligament

b) S YNOVIAL B URSAE

The subtendinous bursa of the infraspinatus muscle is located between its

terminal tendon and the cartilage-covered lateral surface of the greater

tubercle

The subtendinous bursa of the subscapularis muscle lies between the

inser-tional tendon of its muscle and the shoulder joint capsule

The subtendinous bursa of the triceps brachii muscle is expanded between

the olecranon and the insertion of the triceps brachii muscle

The subcutaneous olecranon bursa is an acquired synovial bursa.

The bicipitoradial bursa lies between the tendon of the biceps and the

radius and is frequently fused with the subtendinous bursa of the brachialis muscle

The subtendinous bursa of the brachialis muscle is located between the

end-tendon of the brachialis and the radius

c) S YNOVIAL S HEATHS

Synovial sheaths protect the tendon of origin of the coracobrachial muscle

(Vagina synovialis m coracobrachialis), and of the biceps brachii muscle in

the intertubercular groove (Vagina synovialis intertubercularis) The latter

is an extension of the shoulder joint capsule with which it communicates The end-tendons of the carpal joint extensors are protected by a synovial sheath (long abductor of digit I) or by synovial sheaths and bursae (exten-sor carpi radialis) The ulnaris lateralis end-tendon and its caudal extension

to the accessory carpal are protected by a synovial bursa The radial carpal flexor end-tendon is protected by a synovial sheath; the ulnar carpal flex-

or by a bursa The digital extensors are protected by synovial sheaths at the carpus, the digital flexors on the digits The deep flexor usually has a syn-ovial sheath at the carpus

Trang 34

131211

9108

9

8 9

1114

12

D

CC19DEE

46

4464

Joints, synovial bursae and sheaths

(dorsal view)

6 Brachialis m

7 Anconeus m.

8 Ext carpi radialis m.

Subtendinous bursa of infraspinatus m.

Articular capsule Synovial bursa

Intertubercular synovial sheath Transverse retinaculum Articular capsule subscapular m.

Subtendinous bursa of Med glenohumeral lig.

Articular capsule

Subcutaneous

bursa olecranon

Subtendinous bursa

of triceps brachii m.

brachialis m.

subtendinous bursa of Bicipito-radial bursa and elbow

collateral lig of Lat and med.

9 Extensor digitalis com m.

16 Supf digital flexor m.

17 Deep digital flexor m.

18 Flexor carpi radialis m

19 Interflexor mm.

Synovial bursae Articular capsules Synovial sheaths

abductor pollicis longus m.

Sesamoid bone of Flexor retinaculum Collateral lig of med carpus Synovial sheath

Articular capsules

A Anular lig of radius

B Dorsal ligg.

C Accessoro-metacarpal ligg.

D Deep palmar carpal lig.

E Palm carpometacarpal ligg.

F Dors carpometacarpal lig.

(see pp 18, 23, 143)

Trang 35

I The m splenius (1), previously transected in its middle, extends from the

spinous processes of the first three thoracic vertebrae to the nuchal crest of

the skull II The m iliocostalis arises from the wing of the ilium and inserts

onto the lumbar transverse process (m iliocostalis lumborum, —24), the

angles of the ribs, and the transverse processes of the last two cervical

ver-tebrae (m iliocostalis thoracis, —17) III Also extending caudally to the

wing of the ilium, the m longissimus is divided along its length into the mm

longissimus lumborum (23), thoracis (16), cervicis (12) and capitis (2)

Cor-responding to their region, these muscles insert onto lumbar transverse

processes, tubercles of the ribs, cervical transverse processes and the

mas-toid process of the cranium respectively IV The m semispinalis capitis lies

in the neck region dorsal to the m longissimus and consists of a dorsal m

biventer cervicis (4), characterized by tendinous intersections directed

trans-versely, and a ventral m complexus (3) Both muscles extend from the

cer-vico-thoracic boundary to the cranium V The m spinalis et semispinalis

thoracis et cervicis (15) lies medial and adjacent to the m longissimus and

courses between the second cervical and eleventh thoracic vertebrae VI

The multipennate mm multifidi extend from the axis to the sacrum In the

caudal half of the neck, the m multifidus cervicis (10) lies deep to the m

complexus and is traversed by dorsal branches of cervical nerves on its

ven-trolateral aspect The m multifidus thoracis is situated deeply, and the m

multifidus lumborum (26) lies deep to the thoracolumbar fascia, adjacent to

lumbar vertebrae and their spinous processes VII At the level of the seventh

lumbar vertebra the m sacrococcygeus (-caud.) dorsalis medialis (27)

con-tinues the oblique pennate m multifidus by means of an approximating

fiber-flow directed caudally VIII The m sacrococcygeus (-caud.) dorsalis

lateralis (25) begins acutely at the fourth lumbar vertebra and, as the

cau-domedial continuation of the m longissimus, proceeds to the tail by a strong

terminal tendon IX The mm interspinales lie deeply between the spinous

processes X The mm intertransversarii (8) are superficial in the neck;

whereas, in the thoracolumbar region they are situated deeply along the

ver-tebral column The mm intertransversarii cervicis are located ventral to the

line of insertion of the m longissimus cervicis XI The mm scaleni extend

from the fourth or fifth cervical vertebra to the eighth rib (m scalenus

dor-salis, —14) and the first rib (m scalenus ventralis, m scalenus medius, —13)

XII The m longus capitis (9) lying adjacent and ventromedial to the mm

scaleni is situated ventrolateral to the cervical vertebrae Arising from the

sixth cervical vertebra it inserts on the muscular tubercle of the occipital

bone XIII The m longus colli (see text-illustration), which appears

plait-ed, is situated ventromedially on the cervical and thoracic parts of the

ver-tebral column Arising on the first cervical vertebra it extends to the sixth

thoracic XIV The m rectus capitis dorsalis major (6) continues cranially

from the spinous process of the axis Between the spinous process of the axis

and the occipital bone it overlies the deeper m rectus capitis dorsalis minor

(XV.) XVI The m obliquus capitis caudalis (7) extends from the lateral

sur-face of the spinous process of the axis to the dorsal sursur-face of the wing of the

atlas XVII The m obliquus capitis cranialis (5) runs from the wing of the

atlas to the occipital bone

b) The N UCHAL L IGAMENT (11), which is paired, lies dorsomedian above the

processes of the second cervical and first thoracic vertebrae Caudally it passes over into the supraspinous ligament The yellow color of the nuchal ligament indicates a predominance of elastic fibers

c) The L UMBAR C UTANEOUS N ERVES form a dorsal, a lateral and a ventral series of cutaneous nerves by means of their serial passage through the stra-

ta of skeletal muscles

I The series of dorsal lumbar cutaneous nerves is formed from nL1 to 4 dl

(dorsal clunial nn.) and becomes subcutaneous approximately 8 cm from the dorsal midline As a rule the nL5 to 7 dl do not reach the cutaneous field of innervation

II The series of lateral lumbar cutaneous nerves arises from branches of the

cranial iliohypogastric (nL1 vl), caudal iliohypogastric (nL2 vl), ilioinguinal (nL2 and 3 vl) and lateral cutaneous femoral (nL3 and 4 vl) nn These nerves pass through the abdominal muscles on a line directed caudodorsally from

the ventral end of the last rib to the tuber coxae The cranial iliohypogastric

n (18, –with accompanying blood vessels), and the caudal iliohypogastric n (19) pierce the m obliquus externus abdominis The ilioinguinal n (20,

–sometimes absent) and the lateral cutaneous femoral n (21, –with

accom-panying blood vessels) become subcutaneous over the dorsal border of the

m obliquus externus abdominis

Chapter 4: Thoracic and Abdominal Wall

1 Muscles of the Vertebral Column, Nuchal Ligament, and Lumbar Cutaneous Nerves

a) The M USCLES OF THE V ERTEBRAL C OLUMN are subdivided into a dorsal

and a ventral group, and a specific epaxial group that moves the head All

the dorsal vertebral muscles (Nos I to X) function in the extension and

lat-eral movement or inclination of the vertebral column The innervation of

all dorsal vertebral muscles and the dorsal muscles that act on the

atlanto-occipital and atlanto-axial joints (‘head movers’, —Nos XIV to XVII) is by

the dorsal rami of the spinal nerves

The ventral vertebral muscles (Nos XI to XIII) flex the vertebral column

and incline it laterally The innervation of all ventral vertebral muscles is by

ventral rami of the segmental spinal nerves The muscles situated ventral to the lumbar part of the vertebral column, namely the mm quadratus lum-borum, psoas major and psoas minor, belong to the sublumbar or inner loin muscles and are dealt with on p 60

M USCLES OF THE V ERTEBRAL C OLUMN

Dorsal muscles of the vertebral column Ventral muscles of the Dorsal muscles moving the head

vertebral column

I m splenius VI mm multifidi XI mm scaleni XIV m rectus capitis dors major

II m iliocostalis VII m sacrococcygeus (-caud.) dors med XII m longus capitis XV m rectus capitis dors minorIII m longissimus VIII m sacrococcygeus (-caud.) dors lat XIII m longus colli XVI m obliquus capitis caud

IV m semispinalis capitis IX mm interspinales XVII m obliquus capitis cran

cervicis et thoracis

1

To demonstrate the muscles of the vertebral column, the skin is removed from the lateral body wall, the dorsum, and the sacral region as far as the dal end of the sacrum Then one removes the remnants of the extrinsic muscles of the thoracic limb The m serratus dorsalis cranialis (33) is detached from its rib insertions and reflected dorsally The thoracolumbar fascia (22, see also text-illustration p 30) is incised longitudinally along a line parallel to and 2 cm from the dorsal midline In the lumbosacral area, the underlying lumbodorsal tendon (39) is incised longitudinally at the same level as the fascia, and a transverse incision is made at the caudal end of the parent cut Then the tendon is detached from the underlying musculature The lumbodorsal ten-don divides at the lateral border of the m longissimus lumborum The deep lamina is directed between the mm iliocostalis and longissimus lumborum as

cau-an intermuscular septum (see text-illustration p 30) cau-and the superficial lamina runs over the m iliocostalis In the neck, the m splenius cau-and m semispinalis are transected after being exposed The sequence to be followed in the dissection of the muscles corresponds to the numeration in the table below

Muscles of the vertebral column

(Cervical and thoracic part)

Trang 36

36 34

36 34 41

41

4139

7 Obliquus capitis cran m.

6 Rectus capitis dors major m.

5 Obliqus capitis cran m.

18 Cranial iliohypogastric n.

19 Caudal iliohypogastric n

20 Ilioinguinal n.

21 Lateral cutaneous femoral n.

22 Thoracolumbar fascia (section)

38 Ext abdominal oblique m.

39 Int abdominal oblique m.

40 Lumbodorsal tendon (section)

41 Cranial clunial nn.

Trang 37

a) The E XPIRATORY M USCLES run to the caudal borders of the ribs, their

fibers being directed cranioventrally They draw the ribs caudomedially

and in so doing narrow the thorax

I The m serratus dorsalis caudalis (2) takes origin from the

thoracolum-bar fascia (see text-illustration) and its fibers course cranioventrally to

insert on the caudal borders of the last three ribs

II The mm intercostales interni (5) lie dorsal to the costochondral

articu-lations and deep to the mm intercostales externi They also appear deep to

the m rectus abdominis in the spaces between the costal cartilages The

mm subcostales and the m retractor costae (34) belong to the system of

internal intercostal muscles As a longer muscle portion, each of the mm

subcostales passes over the medial surface of a rib to insert onto the next

or the next but one The m retractor costae extends from the transverse

processes of the first three lumbar vertebrae to the caudal border of the last

rib

III The m transversus thoracis (13), situated cranial to the diaphragm, is

the cranial continuation of the m transversus abdominis It arises on the

internal surface of the sternum and inserts in a crenate manner onto the

medial surface of each genu costae (bend of the costal cartilage).

b) The I NSPIRATORY M USCLES run to the cranial borders of the ribs, the fiber

bundles being directed caudoventrally They draw the ribs craniolaterally

and widen the thorax

IV The m serratus dorsalis cranialis (3) takes origin from the supraspinous

ligament dorsal to the first eight thoracic spinous processes and terminates

by seven to nine fleshy insertions onto the cranial borders of ribs three to

ten

V At the level of the fourth costal cartilage, the m rectus thoracis (6)

con-tinues the m rectus abdominis cranially It runs obliquely over the

aponeu-rotic origin of the latter as far as the first rib

VI The mm intercostales externi (4) are situated mainly between the

osseous ribs, and extend ventrally as far as the costochondral articulations

at the approximate level of the lateral border of the m rectus abdominis

Only sparse muscle bundles lie further ventrally As the vertebral portions

of the mm intercostals externi, the mm levatores costarum (1) can also be

classified with the system of external intercostal muscles Each of the mm

levatores costarum runs in approximately the same direction from the

transverse process of one thoracic vertebra over the angle of the rib to the

cranial border of the subsequent caudal rib The mm levatores are largely

covered by the mm iliocostalis and serratus dorsalis caudalis

VII The diaphragm is a musculotendinous septum between the thoracic

and abdominal cavities Its tendinous cupola situated ventrally projects a

considerable way into the thoracic cavity The diaphragm functions as the

main respiratory muscle, the contraction of which flattens the cupola

lat-erally The crown of the cupola is fixed at the caval foramen and during

res-piration, its position remains largely constant

The diaphragm is divided into a peripheral muscular portion and a

cen-trally placed tendinous portion, the central tendon The muscular portion

consists of a sternal part (15) inserting onto the sternum, a costal part (13) inserting onto ribs nine to thirteen inclusive, and a lumbar part, the crura

of which insert onto the third and fourth lumbar vertebrae The free

medi-al border of the weak left crus (8) and that of the stronger right crus (7) bound the aortic hiatus (9) This affords passage to the aorta, thoracic duct

and right azygos v The free dorsolateral borders of the crura form the bocostal arches, which are crossed dorsally by the sympathetic trunk and

lum-the ramifying greater splanchnic n The slit-like esophageal hiatus (10)

pro-vides a transit for the esophagus and the accompanying dorsal and ventral vagal trunks It lies in the muscular part of the diaphragm bordering the

central tendon The central tendon (14) is V-shaped and exhibits the

fora-men venae cavae (11) to the right, in the region of the cupola The forafora-men

gives passage to the caudal vena cava

Innervation is by the phrenic n (12), which arises by three roots from the

fifth to seventh cervical nerves The nerve passes over the pericardium and heart at the level of the coronary groove The right phrenic n accompanies

the caudal vena cava, both lying within the plica venae cavae that extends

between the heart and the diaphragm The left phrenic n reaches the diaphragm in a short fold of the mediastinal pleura of the left pleural sac

tran-The respiratory muscles lie upon the thorax and are known therefore as

muscles of the thorax From the functional viewpoint they are divided into

an expiratory and an inspiratory group

The main respiratory muscle, the diaphragm, and the other obligatory

res-piratory muscles, are supported functionally by auxiliary resres-piratory

mus-cles, which have been discussed in connection with other muscle groups,

for example the muscles of the vertebral column The mm scalenus and

serratus ventralis are auxiliary inspiratory muscles and the m iliocostalis and abdominal muscles are auxiliary expiratory muscles, although some authors consider the mm scalenus to be obligatory Keeping in mind their positional relationship to the thorax, the obligatory respiratory muscles are also divided into external, middle and internal respiratory muscles

The innervation of the diaphragm is provided by the phrenic n of its

respec-tive side and that of the remaining respiratory muscles by intercostal nn

R ESPIRATORY M USCLES

II mm intercostales interni incl mm middle respiratory muscles VI mm intercostales externi incl

subcostales and retractor costae mm levatores costarum

hg

c Ext abdom oblique m.

d Serratus dors caud.

e Int abdom oblique m.

Trang 38

18

2122

242319

3734

33

38a

b

c ed

f

gh

i

209

29

10

30

1431

(left lateral view)

f Dorsal vagal trunk

g Ventral vagal trunk

h Esophagus

i Caudal vena cava

Trang 39

a) The P REPUCE (P REPUTIUM ) covers the glans penis The caudal part, which

passes over into the haired skin in the region of the body of the penis, is

attached to the ventral body wall The cranial part reaches nearly to the

umbilicus and ends freely, ring-like, passing over at the preputial orifice

into the internal lamina that lines the preputial cavity The prepuce consists

of a haired external lamina (7), which is continuous at the preputial ostium

(1) with the hairless cutaneous mucous membrane of the internal lamina

(8) At the preputial fundus (10), at the level of the greatest circumference

of the bulbus glandis, the internal lamina is reflected onto the glans penis

as the penile lamina (9), which clothes the glans In the fundus region, the

internal lamina and the penile lamina exhibit numerous lymph nodules

With erection of the penis, the penis lengthens, emerging from the prepuce

The internal lamina is drawn cranially onto the lengthened penis, and the

fundus and preputial cavity are then no longer present

b) The M AMMAE lie on both sides of the median intermammary groove and

as a rule consist of five mammary gland complexes per side; namely, a

cra-nial and caudal thoracic mammary gland complex, a cracra-nial and caudal

abdominal mammary gland complex, and an inguinal mammary gland

complex The mammae of the male are characterized by insignificant

mam-mary papillae or teats A mammam-mary gland complex consists of the body of

the mamma with about eight to twenty mammary glands (usually about 12

glands are developed) and a teat (Papilla mammae).

Before birth, from the tip of each teat-anlage, at first several solid

epider-mal buds sprout deeply into the subcutaneous tissue, a process which takes

place in the male sex without recognizable differences At the time of birth,

the epithelial buds contain a lumen

A sex-specific difference becomes distinct only with sexual maturity and

the first estrus Especially under the effect of estrogen, the epithelial sprouts

divide and form a partial lumen Moreover, estrogen brings about the

deposition of fat within the mammary gland This is transitory and later

the fat tissue is replaced by the further development of the epithelial

sprouts into well developed glands In the non-lactating bitch the

glandu-lar and adipose tissue are so slightly developed that the bodies of the glands

exhibit no swelling and can scarcely be separated from one another

With pregnancy, sprouting, ramification and lumen-formation in crease.

This is induced by an elevated blood-estrogen level In the second half of

pregnancy alveoli develop at the ends of these mammary gland canals; this

is brought about especially by the effect of progesterone

During the lactation period, about thirty days in length, the alveoli

guar-antee the secretion of milk Thus, from an individual epidermal sprout a

large gland with alveoli, lactiferous ducts, lactiferous sinus and papillary

duct develops From the alveoli the milk reaches the lactiferous sinus (4)

first by smaller and then by larger lactiferous ducts (3) The sinus is

with-out subdivision by a transverse fold as is typical for larger animals Its

pre-dominant part is in the papilla (Pars papillaris) and extends only with its

initial part, which receives the lactiferous ducts, into the body of the gland

(Pars glandularis) The lactiferous sinus reaches the surface of the body as

a more narrow papillary duct (5) The duct is located in the distal third of

the teat and, usually independent of neighboring glands, opens by a

papil-lary ostium (6) on the end of the teat (Papilla mammae, —2) Erectile blood

vessels of the teat with typical thick-walled (muscular) veins are less

devel-oped in the bitch Smooth muscle cell bundles surround the individual

pap-illary ducts circularly as sphincters

After the lactation period a large part of the duct system, and especially the

glandular alveoli, undergoes involution

The fascial and muscular suspensory apparatus as well as the vascular and

nerve supply of the mammae and prepuce are alike in many ways and, for

that reason, are studied together

I The suspensory ligament of the mammae or, respectively, of the penis

(20) as the continuation of the deep fascia of the trunk splits off at the

lev-el of the linea alba and passes around the mammary complex or into the

prepuce and around the penis as the fascia penis The cranial

supramam-mary muscle (female) or cranial preputial muscle (18, —male) arises from

the linea alba at the level of the xiphoid cartilage and extends onto the basis

of the abdominal mammae or, respectively, into the prepuce The caudal

muscles of the same name are inapparent

With respect to the blood and lymph vascular and nerve supply, there is a

cranial field of supply for the two thoracic mammae and the cranial abdominal mamma as well as a caudal supply field for the caudal abdom-inal and inguinal mammae, or, respectively, for the prepuce, the skin in the region of the penis, and the scrotum Anastomoses occur between the two fields of supply at the level of the umbilicus

II For the cranial thoracic mammae, the blood vessels of the cranial

sup-ply field arise from the lateral thoracic artery and vein (13) and from the

internal thoracic artery and vein Perforating branches of the latter vessels

emerge near the linea alba to supply the two thoracic mammae and end

with the cranial superficial epigastric artery and vein (17) The cranial

superficial epigastric vessels perforate the thoracic wall at the level of the costal arch and, after supplying the cranial abdominal mammae, anasto-mose with the like-named caudal vessels at the level of the umbilicus The

blood vessels of the caudal supply field arise from the external pudendal

artery and vein (26), which, after traversing the inguinal rings and canal,

divide at the level of the inguinal teat into the ventral labial or,

respective-ly, ventral scrotal artery and vein (27) and the caudal superficial epigastric

artery and vein (23) These vessels give off mammary or, respectively,

preputial branches The cranial and caudal superficial epigastric vessels are the main vessels and also take over the supply of the teats Additional con-tributing vessels are the intercostal arteries and veins, the cranial abdomi-nal vessels and the deep circumflex iliac vessels Individual vessel-branches

(predominantly veins) can cross the midline (Linea alba) and take part in

the supply of the contralateral mammae

III The lymph vessels of the cranial supply field run to the axillary (11) and

accessory axillary (12) lymph nodes The lymph vessels of the caudal ply field drain both caudal mammae and the prepuce, the external skin cov-

sup-ering the penis and the scrotum They run to the superficial inguinal lymph

nodes situated at the base of the inguinal mamma where the external

pudendal artery and vein divide into ventral labial or scrotal branches and the caudal superficial epigastric artery and vein

IV The sensory nerve supply is derived from the intercostal nerves

cranial-ly and the cranial and caudal iliohypogastric nerves caudalcranial-ly These approach the mammae by means of lateral cutaneous branches (15 and 21

of the lateral series of thoracic and lumbar cutaneous nerves) and by

ven-tral cutaneous branches (14 and 22) near the linea alba Caudal to the 10th intercostal nerve, no ventral cutaneous branch is dispatched by the thoracic

or cranial lumbar spinal nerves, the ventral skin being supplied by the tral extension of the lateral cutaneous branch and, the inguinal mamma

ven-caudally, by the genitofemoral nerve (24), which traverses the inguinal

canal in the company of the external pudendal artery and vein

c) Before commencing the dissection, details should be provided on the

R ELATIONSHIP OF THE F ASCIAE (see also pp 36 and 146)

I The superficial and deep fasciae of the trunk are classified as the

exter-nal fasciae of the trunk The superficial trunk fascia is closely united to the

skin and ensheathes the cutaneous muscles of the abdomen by means of

two laminae The deep trunk fascia (19) is intimately united to the surface

of the external abdominal muscle Dorsally, in the lumbar region, it is

known as the thoracolumbar fascia (see p 30), which courses over the

muscles of the vertebral column between spinous and transverse processes

In the midline ventrally, the deep fascia fuses with the linea alba, and there the suspensory ligament of the mammae separates off from it In the inguinal region the external fascia of the trunk (comprising the superficial

and deep fasciae of the trunk) continues as the external spermatic fascia

This envelops the vaginal tunic of the peritoneum externally, and at the

inguinal groove passes onto the thigh as the fascia lata (28).

II By and large, the internal fascia of the trunk is adherent to the serosa

and is known by different terms depending on its location In the thoracic

cavity it is known as the endothoracic fascia, in the abdominal cavity as

transversalis fascia, on the ventral surface of the sublumbar muscles as the iliac fascia, and within the pelvic cavity as the pelvic fascia The internal

fascia of the trunk, or more particularly the transversalis fascia, continues

as the internal spermatic fascia that invests the vaginal tunic of the

peri-toneum

3 Body Wall, Prepuce and Mammary Glands (Mammae)

The remaining skin of the abdomen is removed from both sides of the body, keeping intact the mammae or the penis as the case may be In the bitch, the mammae of the left side are preserved by incising the skin abound the base of each teat Beginning laterally, the mammae of the right side are removed after cutting through the right m supramammarius and the suspensory ligament of the mammae In the male one removes the hairy outer skin adjacent

to the penis and its cranial continuation, the external lamina of the prepuce, while keeping intact the m preputialis cranialis and the suspensory ligament

of the penis The preputial laminae will be cut as shown in the accompanying figure

1

2

Trang 40

3037

34

35

3132

38

3933

40

30

34

3529

38 Ext spermatic fascia

39 Intern spermatic fascia and vaginal process of peritoneum

31 Ext abdominal oblique m

32 Ext (supf.) inguinal ring

33 Caud supramammary m or preputialis

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